Answered by Shaykh Faraz A. Khan
Question: Can I pay fidya and feed the poor to make up for fasts missed during ramadan due to menstrual cycle instead of fasting after ramadan?
Answer: Assalamu alaikum wa rahmatullah,
I pray this finds you in the best of health and states.
No, you must make up the missed days, although there is no time limit for doing so. Space them out over time such that it is easy for you.
Payment of fidya is only an option for the very old, or for one who missed fasting due to a chronic illness from which the person is not expected to recover. In the latter case, one should consult both a physician and a scholar.
[Ibn Abidin, Radd al-Muhtar; Tahtawi/Shurunbulali, Hashiyat al-Tahtawi ala Maraqi Falah]
And Allah knows best.
Checked & Approved by Faraz Rabbani