Does expiation for delaying the making up of Ramadan days become obligatory if the person was unaware of its obligation?

The majority of scholars hold the view that expiation (kaffarah), which is feeding a poor person for each day, is obligatory along with making up the missed days (qada') for anyone who delayed making up Ramadan fasts without a valid excuse until the next Ramadan began. This is based on what has been authentically reported from some Companions.

The Hanafis, however, are of the opinion that only making up the fasts is obligatory, without the need for expiation, citing Allah's statement: "a [like] number of other days" (Quran 2:184). The preferred view according to us is the obligation of expiation in cases of negligence, but it does not multiply with the multiplication of years.

If you were ignorant of the prohibition of delaying the make-up fasts, then no expiation is due from you. However, if you knew of its prohibition but were unaware of the obligation of expiation, then ignorance of the consequences of a forbidden act is not an excuse, and thus the expiation is not waived for you.