Does fasting the day of Arafah—as a makeup for a day I missed in Ramadan—expiate the sins of the past and coming year?

Whoever fasts with the intention of making up a missed fast and with the intention of fasting the Day of Arafah will receive both rewards. However, it is better to fast one day for the make-up fast and another day for Arafah with the intention of a supererogatory fast.