All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
A person who has sex with his wife during the day of Ramadan, his fast becomes null and void. On the other hand, he is required to expiate his sin either by freeing a slave, failing that he should observe fast for two consecutive months, failing that he must feed sixty poor people. Moreover, he has to follow the mentioned order of expiation in case of failing short of doing any of the three ways. This is the opinion of the majority of Muslim scholars.
This opinion is based on a narration reported by Al-Bukhari and Muslim from Abu Hurayrah : "A person came to the Apostle of Allaah () and said: 'O Messenger of Allaah! I am doomed'. The Prophet, sallallaahu Alayhi wa sallam, said: 'What has brought about your ruin?' The person said: 'I had a sexual enter course with my wife during the month of Ramadan (i.e. during the day)'. Upon this the Prophet said: "Can you find a slave to set him free? He said: 'No'. The Prophet said: "Can you observe fast for 2 consecutive months? He said: 'No'. The Prophet said: "Can you provide food for sixty poor people?" He said: 'No'. Abu Hurayrah said: 'While we were sitting with the Prophet a large basket full of dates was produced to the Prophet . So, the Prophet said: "Where is the inquirer?" He said: 'Me'. The Prophet said: "Take this and give it as charity".
This also means that if such a person is not able to pay the expiation, it is permissible for someone to pay on his behalf as long as the first accepts, and this will be sufficient. But, if such a person does not expiate by all means, it is still his duty until he can do so. Then, when he can pay the expiation, he should feed the sixty poor people. Also, one can do such an expiation in his own homeland and this is better, since transferring the expiation to another country is permissible. This ruling of transferring the expiation is in contrast with paying Zakah, which should be paid in the country where a giver lives unless there is some benefit, such as poor relatives in dire need, or no need exists for it where the giver lives.
Allaah Knows best.