This is the approved revision of this page, as well as being the most recent.
There’s a Torah obligation to say Shema once in the morning and once at night as it says “VeDibarta Bam…BeShovkacha Uvkumecha”. 
There’s a dispute about how much of Shema is Deoritta and we hold only the first pasuk is Deoritta and next three paragraphs are Derabbanan. 
Earliest time and Vatikin
The ideal time for Shema is to say Shema a little before HaNetz (sunrise) so that one can juxtapose Geulah to Tefilah and start Shmoneh Esrei at HaNetz. This is the practice of the Vatikin (those who fulfill the מצות early and in the proper time).
The earliest time for shema or Brachot shema is when one can recognize an acquaintance from 4 amot away called Mesheyakir, which is one hour (in Shaot Zmaniot) before HaNetz HaChama. Preferably, one should say it later since some hold the earliest time is closer to HaNetz HaChama. Additionally, the earliest time for Shmoneh Esrei is HaNetz HaChama unless it’s a Shat HaDachak (pressing need) and so one will need to wait a long time between saying Shema and Shmoneh Esrei and will not be able to juxtapose Geulah to Tefilah. 
If one is in extenuating circumstances so that one will not be able to say Kriyat Shema (even just to say the first פסוק of Shema and the following one until Ad Livavecha) after MeSheYakir with any Kavana (proper intent) because one will be traveling, one may say it after Olot Hashachar. 
If one has a pressing need meaning that he traveling to a dangerous place or that he’s traveling and the group won’t wait for him at all, and one knows that he will not be able to have kavana to say the first parsha of Shema later, one can say Shema at Olot HaShachar (72 minutes in Shaot Zmaniot before HaNetz earlier than one is able to recognize an acquaintance from 4 amot). 
If one will be traveling to work at dawn and will not be in a place where it’s possible to say Shema with Kavana one can say Shema at Olot 
If one know that one will not be able to have any Kavana when the time comes for Shema he is allowed to say it from Olot. 
In a Shat HaDachak at Olot HaShachar, one can only say Shema with the Bracha of Ahavat Olam/ Ahava Rabba. When the time for Shema comes, meaning an hour before HaNetz, one can Lechatchila say Yotzer Or. If one also says Yotzer Or after Olot he has what to rely on. 
If one said Shema at Olot HaShachar even though it wasn’t a Shat HaDachak has fulfilled his obligation Bedieved unless one is regular to say Shema at Olot HaShachar when it’s not a Shat HaDachak. If one’s regular to say it more than once a month at Olot when not a Shat HaDachak one doesn’t fulfill his oblkigation and must repeat at the proper time. 
Saying Shema of Arvit after HaNetz
If due to an Ones (extenuating circumstance) like a sickness one missed saying Shema at the beginning of night one can say Shema of Arvit with brachot until HaNetz however one doesn’t say the bracha of Hashkivenu after Olot HaShachar. 
If due to an Ones one said Shema of Arvit after Olot then one can’t Shema of Shacharit before HaNetz (not even at the time of MeSheyakir, an hour before HaNetz) even if it’s a Shat HaDachak since he already established that time as night by saying Shema of Arvit. 
If one doesn’t say Shema at HaNetz one should say it as soon as possible. However one shouldn’t say it earlier beyachid if one can say it later with a minyan before the latest time for Shema. 
Latest Time of Shema
The latest time for Kriyat Shema is the end of the third hour (in Shaot Zmaniot) which is a quarter of the day. 
Even though the primary time for the latest time of Shema is the third hour of the day according to the Gra, one should be strict for Magen Avraham to say before the third hour according to his calculation.
The latest time for the nighttime Shema is Chatzot. However, if didn't say before Chatzot one can still say it until Olot Hashachar.
Latest Time for Brachot Kriyat Shema
If one didn’t say Shema before the third hour, one can still say it with Brachot until the end of the fourth hour; but one doesn’t fulfill Shema in it’s proper time. 
If one didn’t say Shema before the fourth hour one should say it without Brachot until the end of the day. Ashkenazim can say it with Brachot until Chatzot if it was an ones (unforeseen circumstance).  Woman have the same halacha as men with respect to this halacha.
After the fact one make the Brachot Shema until the end of the fourth hour according to the Gra. 
Making up Shema after the entire day passes
If one didn’t say Shema during the day there’s no way to make-up by saying it twice during the night and certainly one shouldn’t say it twice at night with Brachot. 
The time of the Magen Avraham and Gra
There’s a dispute of how to measure the day, some count the day from Olot Shachar until Tzet HaKochavim (Magen Avraham) and some count it from HaNetz/Zerichat Hashemesh until Shekiah (Gra). By Deoritta laws (including Kriyat Shema) one should be strict like the time of M”A, but if it’s Shat Hadachak one has what to rely on to go like the time of the Gra. 
One shouldn’t say Kriyat Shema without the Brachot, however if one will miss the time, one should say it without Brachot, and then when one gets up to Shema again one should say it with the Brachot. 
If one’s in doubt whether one could finish Shema with Brachot in time, one should say Shema without Brachot with the following stipulation: “If I won’t complete Shema with Brachot in it’s time, I intend to fulfill my obligation to say Shema now. If I will be able to complete Shema with Brachot in it’s time, my reading now should be like reading Torah and I want to fulfill my obligation only with my reading with Brachot later on.” 
If you are concerned that if you daven with the congregation you will miss sof zman Shema according to the Magen Avraham then you should say Shema beforehand (during Lolam Yehey Adam) with kavana. According to Ashkenazim this can be done without any stipulation and according to Sephardim one should do this with a stipulation that “if the halacha is like the Magen Avraham I want to fulfill my obligation now and if not I don’t”.
One should say Shema on time even if one will have to pray Beyachid (without a minyan). 
Saying Shema without Tefillin
It is forbidden to say Kriyat Shema without Tefillin. Doing so is like one is testifying false testimony against oneself since in Shema it says to wear Tefillin and one isn't practicing what one is saying. After the fact one does fulfill one's obligation even if one said Shema without Tefillin.
If one doesn’t have Tallit and Tefillin and is going to miss the time for Kriyat Shema one should say Kriyat Shema with Brachot in time and then repeat it with Tallit and Tefillin without Brachot. The same is true even if one is unsure whether one will miss the time for Kriyat Shema. 
It is permitted to say Kriyat Shema without wearing Tzitzit.
If one is planning on saying Shema later with Tefillin, some say that it is permitted even initially to say Shema without Tefillin, while others hold that it is forbidden.
Women are exempt from Kriyat Shema  however it is proper  that women say the pasuk of Shema Yisrael  (and Baruch Shem) .
A groom the night of his wedding is obligated to say the Kriyat Shema. 
Doing a task at the time of Kriyat Shema
If someone started a task before the time of Kriyat Shema began (at Olot HaShachar) he may continue as long one will have time after the work to say Kriyat Shema. 
However, if someone started a task after the time of Kriyat Shema he must stop immediately. 
One should read the first Pasuk out loud by everyone in the congregation in order to inspire Kavana. 
The rest of Shema should preferably be said out loud. It can be said quietly as long as one is saying it loud enough that one can hear oneself. After the fact if one said it so quietly that one couldn't hear oneself one fulfilled one's obligation.
When one says the first pasuk of Kriyat Shema, one should instill in one's heart love of Hashem. 
One should read Kriyat Shema with the tune of Torah reading. Such is the Minhag of Sephardim and some Ashkenzim, however some Ashkenazim have the Minhag to not say it with the tune. However one should still pasue in the proper places not to mess up the meaning of the words. 
Ideally one should enunciate each letter clearly, but if one didn't, he nevertheless fulfilled his obligation. 
One should be particularly careful that if the last letter of one word and the first letter of the next work, like bichol livavicha or vaavaditem miheira, to pronounce clearly that it is two different words.  One should also be careful when the last letter of a word in mem and the first letter of the next word is an aleph like uzichartem et, that he doesn't make it sound like the mem belongs to the next word and he is saying met. 
One shouldn't say Shema without wearing Tefillin. However, if can't put them on because one is traveling and it is too difficult to put them on or because one doesn't have them, one shouldn't miss saying Kriyat Shema because of not having Tefillin on.
There is a practice to gather all four Tzitziyot when one gets to the words “MeArbah Kanfot HaAretz” or "Maher Vaheve Alenu" and hold them in your left hand. When one gets to third paragraph of Shema one transfers the strings into one’s right hand , or both hands  while holding onto the knots with one’s left hand until “VeNemanim VeNechmadim Laad” when one kisses the tzitzit and lets go of the tzitziyot.  This is true for a blind man as well. 
Some say that one should gather only the two in front of him, while others say all four 
Since the mitzva of tzitzit is a daytime mitzva, they are not held during the shema at night. 
When one says “UKeshartem LeOt Al Yadecha” one should kiss the Tefillin Shel Yad. When one says “Vehayu LeTotafot Ben Eiynecha” one should kiss the Tefillin Shel Rosh. 
Kavana one needs for Shema
Besides Kavana that one has to fulfill the positive Mitzvah to say Shema (since we hold Mitzvot need Kavana), one needs to understand what one is saying in the first pasuk of Shema because of the Kabalat Ol Malchut Shamayim (acceptance of yoke of heaven) and Yichud Hashem (knowing the Hashem is one).  However, in the rest of Shema one only needs Kavana to say the words (not to be Metasek, accidentally doing the action). 
When saying the word "Echad" one should think that Hashem is master of the four directions of the world, up and down.
One should extend saying the word Echad but one shouldn't extend it so long so that it doesn't sound like a normal pronunciation of the word Echad.
One could have the kavana for the pasuk of Shema Yisrael prior or after saying the pasuk besides while saying it.
Doing Activities During Shema
It is forbidden to walk while saying the first pasuk of Shema and baruch shem kavod. Some are strict not to walk while saying the first pasuk until after Al Livavecha.
It is forbidden to do any activity such as work and even signalling with one's eyes or fingers, or mouthing with one's lips while saying the first paragraph of Shema.
Interruptions in Shema
In the middle of a paragraph one can interrupt to greet someone who deserves fear such as a father or rebbe, and respond to a greeting of someone who deserves respect such as a Talmid Chacham and all the more so someone who deserves fear.
In between paragraphs one can interrupt to greet someone who deserves respect or fear and respond to the greeting of anyone.
Even in the middle of a pasuk one should interrupt Shema for answering Kaddish, Kedusha, Barchu, and Bowing and saying Modim Anachnu Lach at Modim Derabbanan. 
Kaddish is only answered until d'amiran b'alma which for Ashkenazim is the third point of answering Amen and for Sephardim it is the fifth. One shouldn't answer Titkabel, Yehey Shelama, or Oseh Shalom one shouldn't answer Amen since those are only a minhag.
Amen yehey shemey rabba is answered until the words "leolam uleolmey olmaya". Sephardim continue with the word Yitbarach and between paragraphs of Shema if they heard Kaddish they would even answer until "d'amiran b'alma".
When interrupting for Kedusha one should only interrupt for the pesukim Kadosh Kadosh and Baruch Hashem and no more.
If someone hears thunder in the middle of Shema he shouldn't interrupt to recite the bracha on thunder unless he is between the paragraphs.
One shouldn't interrupt Shema for the 13 Middot of Vayavor. One shouldn't interrupt Shema to say the pasuk of Vezot Hatorah during Hagbah but one can look at the Sefer Torah and think about the pasuk.
According to Ashkenazim if someone is called up for an aliya in middle of Shema he can take it but he shouldn't read along with the baal koreh or ask for a mi sheberach. According to Sephardim he shouldn't take the aliya.
If he is the only one who knows how to be the baal koreh he can do so even in middle of Shema.
In the middle of the first pasuk of Shema and Baruch Shem he should not make any interruption.
If one is already sitting there is no question that one may remain sitting for Shema. Even if one was standing but is only up to the bracha of Ahava Rabba before Shema one may sit.
At Shacharit if he is standing he is allowed to sit. Some say he is not allowed to sit.
At Shacharit if he is sitting he is not allowed to stand. After the fact one fulfills one’s obligation. If he is doing so to improve his kavana, such as if he is tired and wants to stand, some say it is permitted and others say it is forbidden.
At Arvit if he is sitting he is not allowed to stand.
At Arvit if he is standing some say he is not allowed to sit.
↑The sources for Kriyat Shema is found in Devarim 6:7. There’s a dispute in the Gemara (Brachot 21a) whether Shema is Deoritta. The Rishonim are in dispute of what we hold. Rav Amram Goan 1:21 pg 102b, Tosfot (Sukkah 11a s.v. Rav Amram, Sotah 32a s.v. Kriyat Shema Utefilah, 32b S”H Urebbe), Teshuvat HaRosh 4:21 hold it’s only derabanan. However Piskei HaRosh (Brachot 3:15), Rif 12a, Rambam Hilchot Kriyat Shema 2:13, Tur and S”A 67:1 all hold it’s a deoraitta.
↑Even among the Rishonim who hold Shema is Deoritta there are many different opinions on how much of it is deoraitta. The Ramban (Milchamot Rosh Hashana 3e) says it’s just the first pasuk, Talmedei Rabbenu Yonah 7b in name of the Rif says it’s the first paragraph. However Baal Hamaor and Raavad argue that the Rif holds it’s only the first pasuk. Ohel Moed 21a quotes that Rabbenu tam holds all three paragraphs are deoraitta. Pri Chadash 67 s.v. Ume’atta says the Rambam holds the first two paragraphs are deoraitta, while Sh”t Shagat Aryeh (Siman 2) argues Rambam only holds the first paragraph and the Sh”t Rashba 1:320 says the Rambam holds it’s just the first pasuk. The Bet Yosef 63e rules that only the first pasuk is Deoritta.
↑S”A 58:1 rules that it’s the most preferable way to do the mitzvah like the Rambam (Kriyat Shema 1:11-12) and most rishonim to say Shema a little before HaNetz (sunrise) so that one can juxtapose Geulah to Tefilah and start Shmoneh Esrei at HaNetz. Mishna Brurah 58:6 and Kitzur Shulchan Aruch 17:1 concur.
Brachot 9b records the dispute between Abaye who holds the time for Shema is shortly before HaNetz as the practice of the Vatikin and Rav Huna who allows from when one can recognize an acquaintance from 4 amot.
There are three approaches in the Rishonim how we hold. Rambam (Keriyat Shema 1:11-12) holds like Abaye that one can say it shortly before HaNetz and in Shat HaDachak one can say it from Olot Hashachar. The Bet Yosef 58, Bach 58, and Pri Chadash 58:1 hold that the Rif agrees with the Rambam.
Rosh (Brachot 1:10), Talmedei Rabbenu Yonah 4b, and Rashba 9b hold that Lechatchila one can say it at Olot but it’s preferable to wait until shortly before HaNetz. So agree majority of the Goenim and Rishonim including Siddur Rav Amram Goan 15 pg 90, Siddur Rashi 8-9, Sefer Chinuch 420, Tosfot Yoma 37b s.v. Abaye, Ramban (Milchamot beginning of Brachot), Or Zaruh (Kriyat Shema 1:13), Meiri (Brachot 9b), Nemukei Yosef (Brachot 9b), Rashbetz (Brachot 9b), Ritva (Brachot 9b, Yoma 37b), and Tur 58.
Rabbenu Chananel (Brachot 9b) holds one should say Vatakin by saying Shema specifically at HaNetz and not shortly before. This is also the opinion of Bal Hamoar (Beginning of Brachot), Roke’ach 3320 pg 211, and Avudraham (Shacharit Chol 1) who says Rabbenu Hai Goan would say the brachot before HaNetz and Shema only at HaNetz, and Rabbenu Tam (Sefer Yashar Sh”t 8:1) holds like Rabbenu Chananel but for a different reason.
S”A 58 and Bach 58 hold like majority of the Rishonim. This is also the opinion of most Achronim. Yet Pri Chadash 58:1, Chisdei David (beginning of Brachot), Ohel Moed (Kriyat Shema 3) argue on S”A and hold like Rambam and Rif. However, Birkei Yosef 58:2 explains that S”A didn’t rule like Rif and Rambam even though usually S”A rules like the majority of the pillars of halacha who are the Rif, Rambam, and Rosh, here he wasn’t sure of the opinion of the Rif as the Rosh and Talmedei Rabbenu Yonah don’t mention his opinion.
Sh”t Ish Matzliach O”C 1:15 pg 42 D”h Vehalah explains that S”A ruled like the Rosh because it was the prevalent Minhag. Concerning Brachot Kriyat Shema, Mishna Brurah 58:1 says based on Rashi (Brachot 11b s.v Yotzer Or) the Brachot Kriyat Shema can also only be said when one can recognize an acquaintance from 4 amot. This is also the opinion of Halacha Brurah 58:2.
Rav Moshe Feinstein in Iggeros Moshe OC 4:6 rules that misheyakir is 35 minutes before sunrise. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise.
↑S”A 58:3. Sh”t Ish Matzliach 1:15 writes that nowadays when we travel in cars, trains, and airplanes this leniency doesn’t apply. However, the Halacha Brurah (Birur Halacha 58:10) writes that this halacha is still applicable to those who have to catch a plane very early and will not be able to say Shema with Kavana (and also it’ll be difficult to put on Tallit and Tefillin at that time).
↑If someone got up before netz and can recite Shema without a minyan, tefillin, and without Shemona Esrei immediately to follow should he recite it then? Rabbenu Yonah 13b s.v. Matniten writes that it is better to say shema before netz than it is to do semicha geulah to tefillah and therefore one should say it before one davens if it is before netz and one isn't going to daven until after netz. Do we hold like Rabbenu Yonah? Shulchan Aruch Harav 58:4 and Rav Schachter (Brachot Shiur 14 (min 68) and Brachot Shiur 17 (min 3)) hold yes. Rav Mordechai Willig (Am Mordechai p. 149-151) argues that we don't follow that opinion since we hold that it is lechatchila to say Shema until the end of the first three hours one shouldn’t say Shema without brachot and without semicha geulah ltefillah before netz. (There is a support for this in the Meiri Brachot 22b s.v. yarad that the mishna only meant if you can say Shema and Shemona Esrei should you say it before netz.)
↑S”A 58:3. On Brachot 8b Rabbi Shimon Ben Yochai says that it’s possible to say Shema twice at night once before Olot for the obligation of night and once after Olot for the day obligation. Rif (Brachot 2b), Rambam (Kriyat Shema 1:12), Rashba (Brachot 9a s.v. LeIyan Hafsaka), Ramban (Milchamot Brachot), and Talmidei Rabbenu Yonah (2b s.v. Iy Nami) write that one should only say it at Olot if it’s Shat HaDachak. Bet Yosef brings the Mahari Ahavuhav who implies this from the Tur. Bet Yosef explains that Tosfot (8b s.v. Lo) holds that one can’t say Shema at Olot but only at when one can recognize an acquaintance. [Bach disagrees and explains that tosfot would agree in a Shat HaDachak]. Bal HaMoar (beginning of Brachot) argues on the Rif and writes that one can’t say it until HaNetz. Magen Avraham 58:4 challenges S”A’s wording that one can say it early if one won’t be able to have kavana in the first paragraph because S”A 63:4 says that one only needs Kavana in the first pasuk.
↑Sh”t Ish Matzliach O”C 1:15(57) says nowadays one shouldn’t say Shema at Olot because one is traveling early. In his comments on Mishna Brurah he writes that there’s what to be lenient if one will be on a train among goyim and will not be able to concentrate. Halacha Brurah 58:9 says that many times he was asked about working situations and he said that one can rely on S”A 58:3 to pray early because otherwise they won’t be able to pray among goyim while traveling or later.
↑S”A 58:3 says in Shat HaDachak one can even say Yotzer Or from Olot HaShachar based on Rashba (Brachot 8b). However Magen Avraham 58:5 argues that the Rashba only holds that way because he holds that one must say the Brachot in order but since S”A 60 holds that can say it out of order one shouldn’t say Yotzer Or after Olot. The Gra agrees and says that so is the opinion of the Rambam (Tamidin UMusafin 6:4). This is also the opinion of Buir Hetiev 58:5, Pri Megadim A”A 58:5, Shulchan Aruch HaRav 58:6, Magen Giborim 58:6, and Mishna Brurah 58:17. However some Rishonim allow Yotzer to be said at Olot including Rokeach 320 pg 210, Nemukei Yosef Brachot 8b, Orchot Chaim (Kriyat Shema 6), and Sefer HaBatim (Kriyat Shema 2:7). Also some Achronim argue with the Magen Avraham including Eliyah Raba 58:7, Levush 58:3, Shulchan HaGavoha 58:9, Siddur Bet Ovad (Kriyat Shema 5), and Kaf HaChaim 58:19.
↑S”A 58:4 rules that Bedieved one fulfills his obligation even though it wasn’t Shat HaDachak based on Rif (Beginning of Brachot), Rambam (Kriyat Shema 1:12), and Rosh (Brachot 1:9). A minority opinion [of Bal HaMoar and Nemukei Yosef Brachot 8b] is that one doesn’t fulfill the obligation even bedieved if it wasn’t a Shat HaDachak. However if one is regular to say Shema at Olot then one doesn’t fulfill his obligation. This is also the opinion of Tur and Bet Yosef 58. Bach 58 says it was left out of S”A because it’s obvious. However Gra 58:10 argues that the Rif holds one does fulfill his obligation. Many Achronim define the time for someone regular to say Shema at Olot as someone who says it once a month including Bach, Sharei Knesset HaGedolah 58:7, Eliyah Raba 58:8, Bear Heteiv 58:6, Mishna Brurah 58:19, Kaf HaChaim 58:20, and Halacha Brurah 58:11 [against Birkei Yosef 58:6 who suggest that saying it twice or three times is called someone regular]. However if one is says it at Olot because of a Shat HaDachak one isn’t called ‘regular’ to say Shema at Olot. So says Chaye Adam 21:3, Mishna Brurah 58:19, Kaf HaChaim 58:16, and Halacha Brurah 58:11.
↑S”A 58:5, however one doesn’t make the bracha Hashkivenu (S”A 235:4 based on Tosfot (Brachot 9a), Mordechai Brachot 1:2, Rambam (Kriyat Shema 1:10), Rosh (Brachot 1:9), and Rabbenu Yerucham 3:2.). On Brachot 8b, Rabbi Shimon Ben Yochai says that it’s possible to say Shema twice at night once before Olot for the obligation of night and once after Olot for the day obligation. Many Rishonim hold that one can only use this leniency if one didn’t say Shema because of an Ones such as an illness (or a state of total drunkenness in which one can’t say Shema) including Talmedei Rabbenu Yonah 2a in name of the Rif, Rambam (Kriyat Shema 1:10), Ravan 135, Meiri, Hagahot Maimon (Kriyat Shema 1:6), Eshkol 1:5 pg 10, Rosh 1:9, Smag (Asin 18 pg 99c), and Smak 104. However some Rishonim say even if it wasn’t an ones Bedieved one fulfills his obligation including Bal HaMoar (Beginning of Brachot), Riaz (Brachot 1:1(4)), Rivivan Brachot 8b, and Ritva (Brachot 9a). S”A 58:5 and 235:4 says one can only fulfill Shema of Arvit after Olot if one was an ones. This is also the opinion of the Acronim including Gra 58:14, Pri Megadim M”Z 58:3, and Halacha Brurah 58:12.
↑this is a dispute in the Achronim if one said Shema of Arvit after Olot before Mesheyakir whether one can say Shema of Shacharit after Mesheyakir before HaNetz. Minchat Cohen (Mevo Shemesh 1:14) and Kaf HaChaim 58:21 say that one can say one Shema before Mesheyakir and one afterwards. Eliyah Rabba 58:9, Pri Megadim M”Z 58:3, Levush 58:5, Erech HaShulchan 58:2, Chaye Adam 34:5, Ben Ish Chai Vaera 4, Mishna Brurah 58:22 and Halacha Brurah 58:13 say if one said Shema after Olot one can’t say Shema of Shacharit before HaNetz.
↑Rosh (Brachot 1:9) writes that logically one should not be able to say Shema of Arvit and Shacharit in the same time period. Rather, says the Bet Yosef 58, one should say Shema of Arvit even if one will miss Shema of Shacharit, because it’s better to passively not say Shema of Shacharit than pass up Shema of Arvit actively by saying Shema of Shacharit after Olot. S”A 58:5 rules like the Rosh. However the Gra 58:14, Pri Chadash 58:5, Eliyah Rabba 58:9, argues that the Tur doesn’t quote this because he holds one can say two Shema’s in one time period. Mishna Brurah 58:21 quotes this opinion as Yesh Cholkin”(some argue). Halacha Brurah 58:13 rules like S”A.
↑Sh”t Ish Matzliach on Mishna Brurah 58 says that it should work without a stipulation because of Safek Sefeka whether the law is like the Rosh and one can’t say Shema twice after Olot, or not and whether this law only applies from Olot to Mesheyakit or until HaNetz. Yet he concludes that it’s preferable one make a stipulation. Halacha Brurah 58:13 argues on the Safek Safeka but seemingly doesn’t argue on the stipulation.
↑Halacha Brurah 58:8 says that one should wait for a minyan if one won’t miss the time for Shema. This is also the opinion of Sh”T Nodea BeYehuda (Kama O”C 3), Mishna Brurah 58:5, Sh”t Eleph Lacha Shlomo O”C 47 that only one will miss the time of Shema should one say it Beyachid.
↑S”A 58, 89:1 based on Rambam in Sh”t Pear Hadar 44 where he writes that all times of Chazal are Shaot Zmaniot. The opinion of the Rambam is also found in Pirush Mishnayot Brachot ch. 1 and in Hilchot Tefilah 3 where he equates 4 hours with a third of the day. This is also the opinion of the Meiri Brachot 9b, Rav Ovadyah MeBarentura, and Sh”t Maharil 163. However Tosfot HaRosh Brachot 3b s.v. Kiyvan writes to calculate the hours equally all year round. See Peni Yehoshua on Brachot who supports the approach of the Tosfot Harosh. The Achronim rule like S”A including Pri Chadash 58:2, Sh”t Shagat Aryeh 5e, Shulchan Gavoha 58:13, Shulchan Aruch HaRav 58:3, Chaye Adam 21:3, Kitzur Shulchan Aruch 17:1, Sh”t Rav Poalim 2:2,3,19, Ben Ish Chai Vaera 5, Sh”t Chesed LeAvraham Teomim Kama O”C 7, Mishna Brurah 58:5, and Kaf Hachaim 58:3.
↑Brachot 9b has a dispute of the latest time for Shema. The Gemara 10b rules like Rabbi Yehoshua who says that it’s the 3rd hour. So hold the Rambam(Kriyat Shema 1:11), Tur, and S”A 58:6. Rambam, Meiri Brachot 9b, Talmedei Rabbenu Yonah 4b hold that after HaNetz until the 3rd hour is only bedieved (after the fact. However implied from majority of Rishonim(including Tur and S”A) is that it’s even Lechatchila. Machsor Vitri (1 pg 7), Yerayim 13, Roke’ach 320, Ravyah 1:15, Rabbenu Yehonatan Melunil (Brachot 1), Siddur Rav Amram 1:15-6 rule the ending time is the beginning of the third hour. However S”A 58:6 rules it’s the end of the 3rd hour based on majority of Rishonim including Tosfot (Avofda Zara 4b s.v. Betelat), Smag (Asin 18), Smak 104, Rambam (Kriyat Shema 1:11), Meharam Rikatani 5, Piskei Rid (Brachot 10b), Piskei Riaz, Eshkol 1:5, Chinuch 420, Meiri (Brachot 9b), Sefer HaBatim (Shema 2:6), Orchot Chaim (Shema 5), Rashbetz (Brachot 10b).
↑Exactly how to calculate the end of the third hour is an argument of the poskim. The gra says that the day begins at sunrise and ends at sunset while the Magen Avraham says days begins at alot hashachar and ends at tzet hakochavim. Mishna Brurah 58:4 quotes both opinions and doesn’t make a ruling. Aruch hashulchan 58:14, Chazon Ish OC 13:3-4, Sh”t Iggerot Moshe OC 1:24, YD 3:129:3, Sh”t Minchat Yitzchak 3:71, all accept the later time of the Gra as the primary opinion. Igrot Moshe YD 4:48:4 writes that although the Gra is primary a person should be strict for the Magen Avraham. See Igrot Moshe 1:24 where he writes that on the charts you should print the Gra's times since that is the primary times. See however, Sh”t Teshuvot ViHanhagot 1:56 quoting Rav Aharon Kotler and Orchos Rabbeinu 1:53 quoting the Steipler.
↑Brachot 9b says if one missed the time for Kriyat Shema one can read it with Brachot. Rambam (Kriyat Shema 1:13), Rif (Brachot 9b), Bahag, Shiltei Giborim (Brachot 10b in name of Smag, Ravyah 25 pg 14, Sefer Chinuch 420, Rid (Brachot 10b), and Riaz Brachot 1:1(7) hold that one can make the Brachot the entire day. However the Rosh Brachot 1:10 quotes Rav Hai Goan that one can only say the Brachot until the 4th hour. This is also the opinion of Rabbenu Chananel (Brachot 10b), Or Zaruha 1:16, Siddur Rav Sadyah Goan 13, Meiri (Brachot 10b), Ravan 139, Tur and S”A 58:6. Most Achronim agree with S”A including Levush 58:6, Bach, Taz 58:4, Petach Dvir 2 pg 18a in name of Rav Chaim Vital, Shulchan Gavoha 58:12, Siddur Yavetz , Gra 58:15, Pri Megadim M”Z 58:4, Shulchan Aruch HaRav 58:10, Chaye Adam 21:3, Kaf HaChaim 58:25, and Halacha Brurah 58:14. However some argue on S”A allow one to say Brachot all day including Sh”t Radvaz 2:156, Pri Chadash 58:6, Rav Chaim Ben Atar in Rishon LeTzion (Brachot 10b), Sh”t Chaim Shal 2:38(70), Keshur Gudal 6:4, and Erech HaShulchan 58:3.
↑Halacha Brurah goes according to S”A that after the fourth hour one can make the Brachot. However Mishna Brurah (Beiur Halacha s.v. Korah Bli Bracha) says one can rely on the Mishkanot Yacov O”C 80 and Maharil to say it with Brachot until Chatzot.
↑Peninei Tefillah 139 cited by Dirshut 58 fnt. 28 quotes Rav Elyashiv as saying that women too if in an unforeseen circumstance can say brachot kriyat Shema after 4 hours until chatzot.
↑Yalkut Yosef 1:109 and Halacha Brurah 58:14 based on a Safek Safeka with many Rishonim that allow one to make the Brachot all day and that Brachot Kriyat Shema may be Deoritta as well as the fact that many Rishonim that say to count the time of the Gra. Even though most of the time a Safek Safeka isn’t enough to make Brachot (Sh”t Yachave Daat 5:21 in the note) here it’s sufficient.
↑The Bet Yosef brings two opinions on the issue: the Kol Bo says some say there’s a way to make up Shema during the night and the Sefer Hashlama holds one can’t make it up the next day. S”A 58:7 writes “If one didn’t say Shema during the day some say one should say Shema twice during the night and if one didn’t say Shema during the night one should say Shema during the day twice and some argue” . The general rule is that when S”A quotes two opinions both with the language “some say” we follow the second one. [Sh”t Avodat Girshoni 114, Knesset HaGedolah (Klalei HaPoskim 62), Sh”t Ginat Veradim (Choshen Mishpat 5:11), Sh”t Bet David O”C 114, and Shulchan Gavoha 17] In our topic Birkei Yosef 58:6, Erech Lechem 58, Levush 108:2, Gra 58:17, Erech HaShulchan 58:4, Shemen HaMoar 58, Shalmei Tzibbor pg 170b, Shulchan Aruch HaRav 58:11, 108:4, Chaye Adam 27:7, Bet Ovad (Tashlumin Achar Arvit 21), Mishna Brurah 58:29, Kaf HaChaim 58:27, and Halacha Brurah 58:15 rule that there’s no way to make up Shema past the day. However, Pri Chadash 58:7, Nachalat Tzvi 108:8, Mekor Chaim 58:7, 80:1, Eliyah Raba 58:12, and Eliyahu Zuta 108:2 say that one should repeat it during the night without Brachot.
↑Many are strict to count from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri Chadash 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), Rav Poalim O”C 2:2, and Kaf Hachaim 58:4. || Majority hold that we count from HaNetz including: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok in Noam 9 pg 235, and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri Chadash rejects his proofs), Shiltei Hagiborim on the Mordechai (Brachot 4:3) (as understood by Magen Avraham 233:3, Mishna Brurah (Shaar Tzion 233:10), and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot Yom Tov (Pesachim 2:3), Rambam Perush Mishnayot, and Biur HaGra 459:2. In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (v. 1 Vaera 3), and Yalkut Yosef 1 pg 98 write that one should be strict to count from Olot in matters of Deoritta and so by Kriyat Shema one should follow the time of Magen Avraham.
↑Sefer Meorot (Beginning of Brachot), Bet Yosef 46, Darkei Moshe 58:3 and Rama 58:4 say that one should say the Shema in it’s time and then repeat it with Brachot. Sh”t Mishkenot Yacov O”C 80 challenges this.
↑Biur Halacha 46 s.v. vyotzei writes that one should say Shema during Lolam Yehey Adam without brachot in order to not to miss Shema according to the Magen Avraham. His logic is that either the Magen Avraham is right and it is critical to say Shema then. Or even if the Gra zmanim are correct, perhaps the Bet Yosef is right and you can always say Shema without brachot early even though one is going to say it in tefillah later before sof zman kriyat Shema.
The Sephardic opinion is based on: Hagahot Rabbi Akiva Eiger 46:9 based on S”A 489:3 concerning Sefirat HaOmer. Yalkut Yosef 1 pg 120 supports this based on a Shibolei Haleket 48. So says Sh”t Avnei Nezer O”C 2:449, Sh”t Tzitz Eliezer 7:4, and Halacha Brurah 58:4.
↑Brachot 14b, Shulchan Aruch 25:4, Olot Tamid 58:1, Eliyah Raba 58:5, Kaf HaChaim 58:11, Halacha Brurah 58:5, and Mishna Brurah (58:5 and 25:14) rule that if there’s no fear of missing the time for Shema one shouldn’t say Shema without Tefillin.
↑Mishna Brurah 25:14 writes that saying Shema without Tefillin fulfills one's obligation. However, the Ateret Tzvi 25:6 argues that the Gemara's expression that Shema without Tefillin is like a Korban without a Mincha implies that one doesn't even fulfill the mitzvah of Shema.
↑Brachot 14b says there that Rav said Shema and then put on Tallit and Tefillin because the person who was bringing his Tallit and Tefillin forgot to bring it by the time for Shema. This is also the opinion of Levush 58:2, Sharei Knesset Gedolah 58:9, Olot Tamid 58:1, Eliyah Raba 58:5, Mishna Brurah 58:5, and Kaf HaChaim 58:11. Mishna Brurah 58:5 and Halacha Brurah 58:5 rule that one should also say Shema without Tefillin if there’s a doubt one will miss the time.
↑Levush 25:1 explains that it is only like testifying false testimony when saying Shema without Tefillin since it is a personal obligation, but Tzitzit which is only an obligation if one is already wearing a four cornered garment but otherwise it is possible to avoid it isn't an issue to say Shema without Tzitzit.
↑Daf Al Hadaf Brachot 14b cites the Bet Yitzchak OC 17:3 who says that it is permitted to say Shema without Tefillin if one plans on putting on Tefillin afterwards. Masef Lchol Machanot 25:31 and Torat Yekutiel 11 agree. However, Chofetz Chaim (Shemirat Halashon ch. 2) argues that it is forbidden even if you’re planning on putting on Tefillin afterwards since it is still false testimony for the time being.
↑S”A 70:1 explains that they are exempt because Kriyat Shema is a Mitzvah Aseh SheZman Grama.
↑S”A 70:1 writes that it’s proper that women accept upon themselves the yoke of heaven. Even though the Bach (70) holds that women are obligated to accept the yoke of heaven daily, the Mishna Brurah 70:1 and Halacha Brurah 70:1 bring many who argue and hold like S”A that it’s only proper but not an obligation.
↑The Rama 70:1 explains it to mean the pasuk of Shema Yisrael. The Nachalat Tzvi 70:1 writes that S”A holds that women should say the first paragraph and the Levush (brought by Mishna Brurah 70:5 and Halacha Brurah 70:1) implies that S”A agrees to the Rama. Halacha Brurah 70:1 rules that both for Ashkenazim and Sephardim it’s sufficient to say the first pasuk.
↑Levush 70:1, Chida in Kesher Gudal 11:3, and Halacha Brurah 70:1 write that women should also say Baruch Shem along with Shema Yisrael.
↑The Mishna (Brachot 16b) writes that a groom of a virgin was exempt from saying Kriyat Shema because he is busy with his mitzvah. However, Tosfot (Brachot 17b s.v. Rav Shisha) writes that since nowadays we don’t have kavanah anyway a groom is obligated to say Kriyat Shema. This is quoted in the Hagahot Maimon (Kriyat Shema 4:2) and Mordechai 2:3. However, Rambam (Kriyat Shema 4:7) rules that a groom is exempt but is permitted to say it if he is able to concentrate. Pri Megadim (E”A 70:2) explains that Shulchan Aruch 70:3 rules like Tosfot that a groom is obligated in Kriyat Shema and it’s not just optional. This conclusion that a groom is obligated in saying kriyat shema is the opinion of most achronim including the Sh”t HaRama 132:1, Levush 70:3, Olat Tamid 70:6, Atert Zekenim 70:3, Bear Hetiev 70:4, S”A HaRav 70:3, Mishna Brurah 70:14, Kaf HaChaim 70:10, and Halacha Brurah 70:4.
↑The Tana Kama in the Mishna Brachot 15a says that after the fact if someone didn't say Shema loud enough to hear himself he fulfilled his obligation. In the gemara 15b Rav Chisda rules like the opinion of Rabbi Yehuda that initially one needs to say Shema loud enough to hear himself but after the fact one fulfilled one's obligation even if it was quieter than that. Shulchan Aruch 62:3 codifies the opinion of Rav Chisda. Shulchan Aruch 61:26 writes that the practice is to say Shema aloud and have the practice to say it quietly. Halacha Brurah 61:9 explains that Shulchan Aruch means that quietly means that everyone says it loud enough that they can hear themselves and loud means that they said it loudly so everyone can hear.
↑Mishna Brurah 25:14 quotes the Sefer Charedim who says that just as one shouldn't say Shema without Tefillin, so too one shouldn't say the first Pasuk of Shema without instilling in one's heart love of Hashem as the pasuk speaks about the command to love Hashem.
↑Talmidei Rabbenu Yonah 8b says that one must say Kriyat Shema with the Torah reading tune. This is also the opinion of the Tur and S”A 61:24. Rama adds that the Minhag Ashkenaz is not to say it with the tune but some are strict in this regard.
↑Shulchan Aruch 62:1. Mishna Brurah 62:2 writes that the reward for being careful in this is that gehenom will be cooled down for you.
↑Shulchan Aruch 61:20 based on gemara berachot 15. Mishna Brurah 61:33 adds that one shouldn't pause for too long because there is a makaf (hyphen), meaning that it is supposed to be pronounced together.
↑Shulchan Aruch 61:21. Mishna Brurah 61:34 extends this to any situation where the mem and the alef are next to each other even when it will not sound like he is saying met, and also to whenever the aleph will get swallowed if you do not take a short pause.
↑Halacha Brurah (24:6 and 60:5) writes that one should take the four corners of the tzitzit when one reaches the words “MeArbah Kanfot HaAretz”.
↑Kaf HaChaim 24:8 quotes Shaar HaKavanot who writes that at the words "Maher Vaheve Alenu" one should arrange his tzitzit so that two corners are in front and two in the back. Afterwards, one should take all four corners in one's left hand. Ben Ish Chai Parashat Shemot Halacha 5 agrees. see also chabad.org for the Chabad minhag
↑Mishna Brura 24:4, Shulchan Aruch Harav 24:4, Magen Avraham 24:1, Kitzur Shulchan Aruch 17:7, Kaf HaChaim 24:8, 18, Halacha Brurah 24:6. According to Ben Ish Chai Shemot Halacha 8, Kaf Hachaim 24:8 one should kiss them before letting go. Tzitz Eliezer 13:3 writes that one who doesn't gather the tzitzit and kiss them during kriat shema is breaking away from the congregation. Maaseh Rav Siman 39 says that the GR"A would not kiss his Tzitzit during Keriyat Shema
↑Shulchan Aruch 61:25 writes that when one says "ureetem oto" he should grab the front two tzitziyot. see also Beit Yosef on Tur 24 and Shulchan Aruch 25:5. Yalkut Yosef 24:6 in the footnotes writes that this was the practice of his father, Chacham Ovadia Yosef zt"l.
However, Sh"t Torah Lishma 39, Kaf Hachaim 24:8, Kitzur Shulchan Aruch 17:7, and Radvaz 3:571 say that one should collect all four
↑Sh”t Rashba 1:344 writes that even though one needs Kavana by every mitzvah by Shema and Shmoneh Esrei one needs also to think about the words. This is also the opinion of S”A 60:5
↑Raah (Brachot 2e) writes that there’s three levels of Kavana; first is not to be Metasek to intend to do the action of the mitzvah such as reading the words of Shema even if his intention is to check that it’s written correctly, then second is Kavana to fulfill every mitzvah, and the third Kavana is to intend every word for Hashem as one is able. This is quoted by Sefer Hashlama, Sefer Meorot, Rav Avraham Alashvili, Shitah Mekubeset, Ritva all found on Brachot 13a, and Avudraham (Siddur Kol Hashana). S”A 60:5 rules that the first Kavana is sufficient for the rest of Shema and the third level of Kavana is needed for the first pasuk of Shema. This is also the opinion of many Achronim including Sh”t Radvaz 4:1094, Magen Avrham 60:4, Pri Chadash 60:5, Eliyah Raba 60:3, Pri Megadim A”A 60:4, Shulchan Aruch HaRav 60:5 and Halacha Brurah 60:17.
↑Shulchan Aruch OC 61:6 writes that you shouldn't extend the word Echad more than the time it takes to think that Hashem is king of the four directions, up and down. Pri Chadash 61:6 posits that the reason is that one might fall behind and miss tefillah with the congregation. Piskei Teshuvot 61:6 writes that one shouldn't extend the eched too long otherwise it won't sound normal. This is similar to the Mishna Brurah 61:21 that one shouldn't overly stress the daled otherwise it doesn't sound normal.
↑Daf Al Hadaf Brachot 13b citing Minchat Shlomo 2:4:14 and Orchot Rabbenu v. 1 p. 53-4
↑Tosfot Brachot 13b s.v. shoel writes that it is permitted to interrupt Shema with Kaddish and Kedusha since it is greater than the importance of greeting someone of kavod. Rosh Brachot 2:5 agrees but quotes the Maharam who argues. He extends it to Barchu as well. Rabbenu Yonah Brachot 7b s.v. Rabbi Yehuda agrees with Tosfot and extends it to bowing during Modim derabbanan and just saying the word Modim. Bet Yosef 66:3 cites the Avudraham who quotes a dispute whether one should say the word Modim or all of Modim derabbanan in middle of Shema. Shulchan Aruch 66:3 rules like the Tosfot, Rosh, and Rabbenu Yonah. Magen Avraham 66:6 adds that answering Modim Derabbanan means answering with the words Modim Anachu Lach.
↑Mishna Brurah 66:19 writes that it is a dispute whether one can recite the bracha on thunder in middle of Shema but he concludes that the Chayei Adama says that one can only do so if one is between the paragraphs. Yalkut Yosef 66:2 agrees with the Chayei Adam.
↑Shulchan Aruch 66:4 writes that if someone is called up for an aliya in middle of Shema he shouldn't interrupt to take the aliyah. He is based on the Rashba 1:185. However, the Mishna Brurah 66:26 writes that Ashkenazim hold that oen can take the aliya but he shouldn't read along with the baal koreh and obviously shouldn't ask for a mi sheberach. Yalkut Yosef 66:5 writes that he shouldn't take the aliya even if he's the only kohen rather he should leave the room.
↑Hagahot Maimoniyot (Kriyat Shema 2:3) writes that it is best to sit for Shema. Darkei Moshe 63:2 cites this. Kaf Hachaim 63:6 writes that based on Kabbalah it is best to sit for Shema. Yafeh Lelev 63:2 and Kaf Hachaim cite some midrashim that point to the fact that it is fitting to sit for Shema. Midrash Chazit on Shir Hashirim 2:9, p. 46 writes that as a reward for the fact that Avraham was ready to serve the guests Hashem told him to sit and He would reside over Avraham, so too when we say Shema we can sit while Hashem's presences rests above us. However, see Halacha Brurah 63:3 in the footnote where he cites the practice of the Chatom Sofer to stand for all of davening from Baruch She’amar through Shemona Esrei since in his opinion it was more respectful.
↑Ateret Zekenim 63:2 permits and Eliyah Rabba 63:4 writes that he was discussing Shacharit and Arvit. The Magen Giborim 63:2 writes that it is forbidden to sit if one is standing by Arvit but not for Shacharit. However, the Pri Megadim E"A 63:2 writes that it is forbidden to sit if one is standing even at Shacharit so that one doesn't make a mistake and do the same at Arvit. The Mishna Brurah 63:7 accepts the opinion of the Pri Megadim.
↑Rav Amram Goan cited by Tur 63:2, Shulchan Aruch 63:2, Bach 63:2, Halacha Brurah 63:3. The explanation for this halacha is that by standing one is demonstrating that one is following the opinion of Bet Shamay and since we follow Bet Hillel it is incorrect to disregard Bet Hillel and follow Bet Shamay (Brachot 11a, Shulchan Aruch Harav 63:2).
↑Tosfot Brachot 11a understands that if one was strict for Bet Shamay one fulfilled one’s obligation but Rabbenu Shemaya said that one didn’t fulfill one’s obligation. The Kaf Hachaim 63:8 writes that one does fulfill one’s obligation.
↑Ateret Zekenim 63:2, Eliyah Rabba 63:4, Chesed Lalafim 63:2, Ben Ish Chai Vaera 15, Kaf Hachaim 63:9, Halacha Brurah 63:4