Is it wajib for a husband to pay for zakat fitrah on behalf of his ex-wife and a wife who is nusyuz?
Alhamdulillah, praise and thanks to Allah for the countless blessings He has blessed us all with. Blessings and salutations to the Prophet Muhammad PBUH, his wives, his family, companions and all those that follow his teachings to the day of judgement.
Zakat fitrah is a form of zakat which is wajib to be paid by each Muslim individual who fulfils its conditions every year. This is in accordance with a hadith narrated by Ibn Umar RA:
فَرَضَ رَسُولُ اللَّهِ صلى الله عليه وسلم زَكَاةَ الْفِطْرِ صَاعًا مِنْ تَمْرٍ، أَوْ صَاعًا مِنْ شَعِيرٍ عَلَى كُلِّ عَبْدٍ أَوْ حُرٍّ صَغِيرٍ أَوْ كَبِيرٍ
Allah's Messenger (ﷺ) enjoined the payment of one Sa' of dates or one Sa' of barley as Zakat-ul-Fitr on every Muslim slave or free, for every young and old person
Sahih al-Bukhari (1503) and Sahih Muslim (2326)
Zakat fitrah is wajib to be paid by those who are obligated to provide for nafaqah either through a marriage like wife and children, or blood relation like his mother, father and other relatives or due to service provided like the slaves. This is based on a legal maxim:
كُلُّ مَن تَلْزَمُهُ نَفْقَةُ غَيْرِهِ تَلْزَمُهُ فِطْرَتُهُ
“Every person whom are obligated to provide for nafaqah is obligated to pay for their zakat fitrah” Refer Taqrirat al-Sadidah - Qism Ibadah (pg. 419).
Pertaining to the ruling of paying zakat fitrah for one’s divorced wife, Imam al-Nawawi Rahimahullah has explained on this matter where he said: “It is wajib for a husband to pay zakat fitrah for his divorced wife with raj’ie  and ba’in  talaq if the wife is pregnant the same as when the husband is obligated to provide for her nafaqah. While for a wife who is divorced by bai’n talaq and is not pregnant, then it is not wajib for the husband to pay for her zakat fitrah.” Refer al-Majmu’ Syarh al-Muhazzab (6/117).
Pertaining to a wife who is being nusyuz until the sun sets on the night of Eid al-Fitr, then it is not wajib for the husband to pay for her zakat fitrah as he is not obligated to provide for the nafaqah of a nusyuz wife. Refer al-Majmu’ Syarh al-Muhazzab (6/114), al-Hawi al-Kabir (4/386), al-Anwar li A’mal al-Abrar (1/206), al-Mu’tamad fi Fiqh asy-Syafi’e (2/97)
It is wajib for a husband to pay for zakat fitrah of his divorced wife as it is wajib for him to provide for her nafaqah even if the wife is divorced with raj’ie or ba’in talaq if she is pregnant because for both circumstances she is in her iddah state.
However, for a wife who is divorced with ba’in talaq and is not pregnant, or a nusyuz wife, then it is not wajib for the husband to pay for her zakat fitrah the same as it is not wajib for the husband to provide for her nafaqah.
May Allah SWT give us all goodness and true understanding in understanding His Shari’a as well as granting us strength for us to practice it. Amin.
 Raj’ie talaq means a talaq which can be revoked while the wife is in her iddah state. Talaq pronounced by a husband is considered as raj’ie if it is a first and second talaq.
 Bai’n talaq is divided into bai’n kubra and ba’in sughra. Bai’n kubra is a talaq which takes place three times. The couple cannot reunite or remarry each other forever, unless when the wife marries another man, had intercourse, then, they get a divorce or her husband passes away. Only then the first husband is permissible to remarry her.
Bai’n sughra talaq is a talaq pronounced by a husband less than three times, but the couple cannot be reunited unless with a new solemnization, even if the wife is still in her iddah state. Among the bai’n sughra talaq is: Talaq ruled by a judge, talaq through khulu’ and talaq which is ruled by hakim through fasakh.