SHAFAQNA – The Grand Ayatollah Shobairi Zanjani answered a question about breaking fast for supposing the monthly period started.
Question: If a woman breaks her fast supposing she is having her monthly period but later on finds out she was not, what is her duty about the lost days of fasting?
The Grand Ayatollah Shobairi: Must fast later on for days missed but there is no Kaffarah.
Source: PERSIAN SHAFAQNA