Stepfather and Stepmother-Honoring the spouse of one’s parent:[1]

Father’s wife: A person is [Biblically[2]] obligated to honor his father’s wife even though she is not his mother [i.e., stepmother].[3] This applies so long as one’s father is alive, as explained below. [The child is obligated to honor his stepmother with all the forms of honor that he would show his own mother both in speech and action.[4] This obligation to honor the stepmother applies even when the stepmother is not in the presence of her husband who is his father.[5] This applies even if one’s mother instructs him not to honor his father’s wife.[6] Nonetheless, the honor of one’s biological mother comes prior to one’s stepmother.[7] Thus, if both one’s mother and stepmother asked him to bring them a cup of water, he is the first serve his mother prior to his stepmother.[8] Some Poskim[9] rule that the father has the ability to forgive this obligation from his son, and exempt him from needing to respect his wife. However, other Poskim[10] question if he holds the rights of forgiving the honor of his wife that is due from his children. The above obligation is only regarding honoring one’s stepmother, however there is no obligation to fear one’s stepmother. Hence, one may call her by her first name and sit in her seat, unless one’s father is particular in this.[11] After the stepparent passes away there’s no longer any requirement to honor them as is typically done for a parent after death.[12] Nonetheless, one is to follow some of the mourning laws until the first Motzei Shabbos.[13]]

Mothers husband: Likewise, one is [Biblically[14]] obligated to honor his mother’s husband [i.e. stepfather] so long as one’s mother is still alive.[15] [This applies even when the husband is not in the presence of his mother.[16] Nonetheless, the honor of one’s mother comes prior to the honor of her husband.[17] Some Poskim[18] rule that the mother has the ability to forgive this obligation from his son, and exempt him from needing to respect his wife. However, other Poskim[19] question if she holds the rights of forgiving the honor of his wife that is due from his children. The above obligation is only regarding honoring one’s stepfather however there is no obligation to fear one’s stepfather. Hence, one may call him by his first name and sit in his seat, unless one’s mother is particular in this.[20] After the stepmother passes away there’s no longer any requirement to honor them as is typically done for a parent after death.[21]]

After death of parent or after divorce:[22] After the passing of one’s father or mother one is no longer obligated to honor his stepfather and stepmother. Despite this, it remains proper for one to honor them even after the death of one’s father or mother. [However, if one’s stepparent remarried then there is no need to continue to honor them.[23] Likewise, if one’s father or mother divorced their spouse who is one’s stepmother or stepfather, then he is no longer obligated to honor his stepmother or stepfather.[24] If the stepparent passed away while still  married to one’s parent, there’s no longer any requirement to honor them as is typically done for a parent after death.[25] Nonetheless, one is to follow some of the mourning laws until the first Motzei Shabbos.[26]]

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[1] Michaber 240:21; Rambam Mamrim 6:15; Kesubos 83a; Pesakim Uteshuvos 240:54-55; Encyclopedia Talmudit Erech Kibud Av Vaeim Vol. 26 p. 463-465

[2] Implication of Rambam Mamrim 6:15; Ramban on Sefer Hamitzvos beginning of Shoresh 2; Mordechai Bava Basra 3:527; Maharil 81; Chareidim Asei 4:7; See Encyclopedia Talmudit ibid p. 464

Other opinions: Some Poskim rule that it is only a rabbinical obligation. [Meiri Kesubos 103a]

[3] The reason: This is due to the honor that one must show his father. [Ramban on Sefer Hamitzvos beginning of Shoresh 2; Rav Akiva Eiger Kama 68; Kneses Yechezkal 25; Gilyon Maharsha 240:10] See Encyclopedia Talmudit ibid p. 464-465

[4] See Chareidim 12:3; 16:3; Minchas Chinuch 33; Encyclopedia Talmudit ibid p. 464

[5] Maharam Shick Mitzvah 33; Chofetz Chaim Pesicha Aei 10; See Encyclopedia Talmudit ibid p. 464 footnote 1217

[6] Maharam Ben Chaviv 112; Birkeiy Yosef 240:16; Teshuvah Meahavah 370; Ben Ish Chaiy Shoftim 2:28; See Encyclopedia Talmudit ibid p. 467 footnote 1265

[7] Halachos Ketanos 1:28; See Encyclopedia Talmudit ibid p. 467

Other opinions: Some Poskim rule that both the mother and stepmother are equal in this matter. [Meiri  and Mahariy Beirav Kiddushin 31a; See Encyclopedia Talmudit ibid p. 467 footnote 1264]

[8] Chut Hameshulash Parshas Vayigash and Yisro; Minchas Chinuch Mitzvah 33; Maharshag 2:200; See Encyclopedia Talmudit ibid p. 467

[9] Minchas Chinuch Mitzvah 33:1; See Encyclopedia Talmudit ibid p. 465

[10] Darkei Moshe 240:7

[11] Chasam Sofer Kesubos 103a; Chasan Sofer 84; Betzel Hachochmah 3:95

[12] Minchas Chinuch Mitzvah 33:1; See Encyclopedia Talmudit ibid p. 466

[13] Teshuvah Meahavah 1:175; Pischeiy Teshuvos 374:3

[14] Implication of Rambam Mamrim 6:15; Ramban on Sefer Hamitzvos beginning of Shoresh 2; Mordechai Bava Basra 3:527; Maharil 81; Chareidim Asei 4:7; See Encyclopedia Talmudit ibid p. 464

Other opinions: Some Poskim rule that it is only a rabbinical obligation. [Meiri Kesubos 103a]

[15] The reason and source: This is learned from the words in scripture [Shemos 20:12] “Es Avicha” and Es Imecha,” as the extra words Es by both the father and mother comes to include also one’s father’s wife and one’s mother’s husband. [Taz 240:18; Kesubos 103a] It is disputed amongst the Poskim if this obligation to honor the older brother is due to an intrinsic respect that is due to the elder brother, or simply due to the respect of the parents. The practical modification between these two approaches is regarding if one must do so even after the death of the parents. [See Sefer Hamitzvos Shoresh Hasheiyni for a dispute between the Rambam and the Ramban in this matter; Kneses Yechezkal 25; Pischeiy Teshuvah 240:18]

[16] Maharam Shick Mitzvah 33; Chofetz Chaim Pesicha Aei 10

[17] Minchas Chinuch Mitzvah 33:1; Maharshag 2:200

[18] Minchas Chinuch Mitzvah 33:1

[19] Darkei Moshe 240:7

[20] Chasam Sofer Kesubos 103a; Chasan Sofer 84; Betzel Hachochmah 3:95

[21] Minchas Chinuch Mitzvah 33:1

[22] Michaber ibid; Rambam Mamrim 6:15; Kesubos ibid based on Rabbeinu Hakadosh who instructed his sons in this matter; Tur 240 “It is a Mitzvah to honor them after death”; Tzeida Laderech Mamar 1:4-15; Zichron Yehuda 78; See Encyclopedia Talmudit ibid p. 465-466

Other opinions: Some Poskim rule that it is a rabbinical obligation to respect one’s step parent even after the death of the parent that they had married. [Semak Mitzvah 50; Chayeh Adam 67:22; Meiri Kesubos 103a; Shut Haranach Mayim Amukim 50; Chareidim Lavin 32]

[23] Chasam Sofer E.H. 2:128

[24] See Encyclopedia Talmudit ibid p. 466

[25] Minchas Chinuch Mitzvah 33:1; See Encyclopedia Talmudit ibid p. 466

[26] Teshuvah Meahavah 1:175; Pischeiy Teshuvos 374:3

[27] Chareidim 18:1; See Encyclopedia Talmudit ibid p. 464

[28] See Michaber Y.D. 240:21; Michaber 240:19; Kiddushin 32a; Pesakim Uteshuvos 240:54