This is the approved revision of this page, as well as being the most recent.
Laws of Kaddesh
- As with every Kiddush, before reciting the kiddush, one should cover the matzot that are in front of him.
Who is obligated in the mitzvah?
- Kiddish of Yom Tov is made over the first cup of wine of the Seder. Therefore even though by Kiddish on Friday night one person can fulfill the obligation of everyone else by drinking the cup, on Pesach night there’s a separate obligation on everyone to drink the four cups of wine. 
- Women are also obligated in the mitzvah of four cups of wine because they were also part of the miracle. 
- It's preferable to give the children who reached the age of Chinuch a cup for the four cups of wine.
Sitting or Standing for Kiddush
- It is proper to sit for Kiddush. Vayichulu should be recited standing since it isn't part of the Kiddush.
Text of the Kiddish
- If Pesach night falls out on Friday night, we add in Vayichulu to Kiddush.
- If Pesach night falls out on Saturday night, the Kiddish and Havdalah is combined in the following order of the Brachot: (1) Borei Pri HaGafen, (2) HaMekadesh Yisrael VeZmanim, (3) Bore Meorei HaEsh, (4) HaMavdil Ben Kodesh LeChol, and (5) Shehecheyanu. (a nemonic is Yaknahaz- Yayin, Kiddish, Ner, Havdalah, Zman) 
- If one forgot to say Havdalah in Kiddish one should finish the brachot of Gaal Yisrael at the end of Maggid and then say Havdalah.
When Can You Start the Seder?
- One shouldn't say Kiddish before Tzet HaKochavim.
- The table should be set before one returns from shul so that he can begin immediately at tzet hakochvim.
- Even one learning in a Bet Medrash should stop to start the meal on time (at Tzet) so that the children will be awake to ask questions.
The Shehecheyanu of Kaddesh
- The Bracha of Shehecheyanu is part of the Kiddish. 
- If one forgot to make the Shehecheyanu during the Kiddish: some hold one can make it anytime afterwards that day and if you remember on the second day of Yom Tov you should fulfill the obligation with the Shehecheyanu of that day's kiddish and if you forgot also then one can say it during the rest of peasch, even if one remembers in the marketplace. However, some argue that one can only make the bracha until one says the bracha of Asher Galanu of the Magid because that fulfills one's requirement.
- If a woman already made Shehecheyanu during the candle lighting some say it's an interruption to answer amen unless one has in mind while lighting the candles that the Shehecheyanu should cover the Yom Tov but not the mitzvah of Matzah and Maror. However others hold it's not considered an interruption and the amen can be answered.
- One should have in mind to fulfill the obligation of saying Shehecheyanu for the mitzvah of Matzah, Maror and Sippur Yetziat Mitzrayim when saying Shehecheyanu in Kiddish.
Drinking the First Cup
- One doesn’t need to wash one’s hands before Kiddish. If one’s hands aren’t clean one should wash one’s hands with a little water (without a bracha).
- In order to display an act of royalty, each person shouldn’t pour their own cup rather someone else should pour the wine for them.
- There is no Bracha Achrona on the first cup of wine.
Singing Kaddesh, Urchatz
- Before each part of the Seder, it's customary to say or sing the order of the Seder (Kaddesh, Urchatz, Karpas...) until the point that one is up to presently.
- Rabbi Eli Mansour pg. 3
- S”A 473:1
- Chazon ovadia pesach page 5. Pesachim 108b rules that everyone is obligated in the four cups of wine of the Seder. Rambam (Hilchot Chametz UMatzah 7:7) and S”A 472:15-16 rule that women are also obligated in the mitzvah. Source Sheet: on docs.google.com
- Shulchan Aruch 472:15 based on the Rosh. Chazon ovadia pesach page 5- 6 says the age of chinuch for this is when the child can understand sippur yiztiat mitzrayim and says that this is the opinion in shulchan aruch harav 272:25.
- The Haggadah of the Roshei Yeshiva (pg 2, 7, 10, and 14) records the practice of Rav Isser Zalman Meltzer, the Steipler, Rav Yacov Kamenetsky, and Rav Moshe Feinstein to sit for Kaddesh of the seder. For more sources regarding sitting for Yom Tov Kiddish in general see the Kiddish page. Mishna Brurah 473:3 implies that Kiddush at the seder is said sitting. Igrot Moshe OC 5:16:8 explains that certainly one should recite the Kiddush of the Seder night sitting since it is an aspect of the four cups which need to be done in a manner of royalty.
- Igrot Moshe 5:16:8
- S”A 473:1
- S”A 473:1
- S”A 473:1
- Rosh Pesachim 10:2 writes that the night of Pesach is special that we don't do the mitzvot before night even though by Shabbat and other Yom Tovim we hold that one can add from the weekdays to the Shabbat or Yom Tov. However, Rabbenu Yehuda Sirlion Brachot 27a s.v. drav writes that it is permitted to have Matzah earlier than the night if you accept Pesach early. Based on the Rosh, Tur writes that one shouldn't eat the meal before night night. Bet Yosef 472:1 quotes the Trumat Hadeshen 137 that rules that even the Kiddish which is part of the four cups of the Seder must be done at night. This is also the opinion of Shulchan Aruch 472:1 that Kiddish and the rest of the mitzvot of the night need to be done during the night. Taz 472:1 emphasizes the reason kiddush needs to be at night is because it is the time when the matzah is to be eaten and it is the primary course of the meal. Magen Avraham 472:1 emphasizes the reason that the kiddush is part of the four cups and that mitzvah also needs to be done at night. Chazon Ovadia pesach page 1 and Chazon Ovadia (teshuva 1) agrees. The Taz 472:1 gives another reason the Kiddish must be done at night; because the Kiddish is done in order to eat the Matzah and have Kiddish BeMakom Seudah, just like the Matzah has to be at night so too does the Kiddish. Chazon Ovadia pesach page 1 says that you don't need to wait until Tzet HaKochavim according to rabbeinu tam's calculation. Chatom Sofer Pesachim 99b is lenient to do kiddush after shekiya before tzet.
- Chazon Ovadia pesach page 1
- Tur and Shulchan Aruch 472:1 based on Gemara Pesachim 109a
- S”A 473:1
- The Magen Avraham 473:1 comments that one can make up the bracha of Shehecheyanu all the days of the peasch just like any other holiday and proves it from Eiruvin 40b which concludes that one can say Shehecheyanu all seven days. However, Sh"t Arugat HaBosem 144 argues that after you make the bracha on the haggadah of Asher Galanu one has fulfilled his obligation of Shehecheyanu because it includes the words "Vahigiyanu HaLaylah HaZeh". The Sh"t Siach Yitzchak and Chazon Ovadyah (Peasch vol 2 pg 29) rule like the Arugot HaBosem and bring a proof from the Orchot Chaim who ask why do we say Vahigiyanu in Asher Galanu if we already said Shehecheyanu implying that Asher Galanu can fulfill the requirement of Shehecheyanu. Source Sheet: on docs.google.com
- Rav Tzvi Pesach Frank in Sh"t Har Tzvi 1:154 quotes those who say that one shouldn't answer amen tothe Shehecheyanu since the woman already fulfill her obligation and it'd be an interruption between the Borei Pri HaGafen and drinking the cup (since there's an obligation of 4 cups even woman are obligated to drink after Kiddish). Rav Frank adds that lechatchila one should be careful not even to hear the bracha in the kiddish because just hearing it can be a Hefsek. Rav Vosner in Sh"t HaLevi 3:69 rules that an amen would be an interruption unless the Shehecheyanu was coming to fulfill some obligation. Therefore on Peasch where the Shehecheyanu is coming for the Matzah, Maror, and Sippur Yitziyat Mitzrayim, an amen isn't an interruption. Rav Ovadyah in Chazon Ovadyah (Peasch vol 2 pg 27) concurs. For this reason, Rabbi Eliezer Waldenberg in Sh"t Tzitz Eliezer 10:19 is lenient that the woman is allowed to even make the bracha again. Rav Shlomo Zalman Aurbach in Sh"t Minchat Shlomo 2:60:24 argues that since Shehecheyanu is part of the established Kiddish it isn't an interruption at all to answer amen. Source Sheet: on docs.google.com
- Chazon Ovadyah (Pesach vol. 2 pg 23)
- Rama 473:1
- Rama 473:1
- Shulchan Aruch O.C. 473:2