A fasting woman menstruating before sunset

Q: What is the ruling on a fasting woman whose period starts just few minutes before sunset? Does this invalidate her Sawm (Fast)?

A: If her period starts before sunset, her Sawm is invalid and she has to make up for it later. However, if her period starts after sunset, her Sawm is valid and she does not have to make up for it.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.