Is it permissible to fast to make up for Ramadan on the day immediately preceding Ramadan, and what is the expiation for doing so?

It is permissible to make up for Ramadan fasts one or two days before Ramadan or on the Day of Doubt. This is an act of fulfilling an obligation, and there is no expiation (fidyah) for it. However, whoever delays making up for Ramadan fasts without a valid excuse until the next Ramadan begins, must pay an expiation of feeding one poor person for each day, unless they were ignorant of the impermissibility of the delay, in which case there is no expiation upon them.