Q:
What is the ruling on a woman who heedlessly and inexcusably did not fast three days of Ramadan in 1396 A.H.? What should she do?
A:
If the situation is as described and this lady did not fast three days of Ramadan out of heedlessness, not because she believed it was permissible to do so, then she has committed a serious major sin by violating the sanctity of Ramadan. Fasting Ramadan is one of the pillars of Islam, because Allah (Exalted be He) says:
O you who believe! Observing As-Saum (the fasting) is prescribed for you as it was prescribed for those before you, that you may become Al-Muttaqûn (the pious - See V.2: 2).
(Part No. 10; Page No. 142) Until He (Exalted be He) says:
The month of Ramadan in which was revealed the Qur’ân, a guidance for mankind and clear proofs for the guidance and the criterion (between right and wrong). So whoever of you sights (the crescent on the first night of) the month (of Ramadan i.e. is present at his home), he must observe Saum (fasts) that month
So she must fast three days to make up for the days that she did not fast. If she had intercourse during the three days she did not fast, she must also offer Kaffarah (expiation) for that day in addition to making up for it. If she had intercourse on two days then she must offer two expiations and make up for two days. The expiation is to free a slave; if that is not possible, then she must fast for two consecutive months; if she is unable to do that then she must feed sixty needy people from the local staple food. She must also seek the forgiveness of Allah and repent to Him; she must observe the fast that Allah has enjoined on her and sincerely resolve not to break her Sawm in Ramadan again. She must also feed one poor person for each of the three days because of her delay in making up the fasts until after the following Ramadan.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.