Inheritance for One Child
22-4-2018 | IslamWeb
Question:
Assalaamu ‘Alaykum; Please calculate the inheritance according to the following information -Does the deceased have male relatives who are entitled to inherit: (A son) Number 1 - The will which the deceased left behind and that is related to his inheritance is: Daughter - Additional information : Execute
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad 
is His slave and Messenger.
If the questioner means that the deceased has a daughter and that he/she had made a will to her from the inheritance, then this is a will to an heir which is Islamically forbidden and it is not effective unless the rest of the heirs approve of it.
However, if the deceased left behind only a son and a daughter, and did not leave any other heir, then the inheritance should be divided between them by Ta’seeb (by virtue of having a paternal relation with the deceased and not having an allotted share, so they get what is left after the allotted shares have been distributed); the male twice the share of the female. In which case, the inheritance should be divided into 3 shares, the son gets 2 shares and the daughter gets 1 share.
Nonetheless, if the deceased left only one son and did not leave a daughter or anyone else, then the entire inheritance is for the son by Ta’seeb.
Finally, it should be noted –dear questioner –that the matter of inheritance is very complex an issue, so a Fatwa is not enough. Rather, the matter should be taken to an Islamic court or presented orally (in person) to the scholars in order to investigate and find out who the heirs are, as it might be that there is an heir who would not be known except after investigation. There might also be a will, debts, or other dues that are not known to the heirs. It is known that people's rights come in priority over the right of the heirs in the inheritance. Therefore, the inheritance should not be divided without resorting to an Islamic court, if any, in order to fulfill the interests of the dead and the live people.
Allah knows best.