Must one complete the fast if menstruation begins during the day?

If a woman menstruates during fasting, her fast is invalidated, and she is obliged to make up that fast if it was an obligatory fast. It is forbidden for her to continue fasting while menstruating. The Ummah has reached a consensus on the prohibition of fasting for menstruating and post-natal women, and that their fast is not valid. They also agreed on the obligation for them to make up the fasts of Ramadan. If menstruation occurs at any part of the day, the fast of that day is invalidated. However, if she feels the onset of menstruation before sunset but it does not appear until after sunset, then her fast is valid and not invalidated.