All praise be to Allah, peace and blessings be upon Prophet Mohammad.
All Muslims are well acquainted with the fact that breaking fast for one day without a lawful excuse is one of the major grave sins that entail seeking sincere repentance from Allah, The Almighty. If a Muslim fails to observe the pillars of Islam (obligatory fasting is one of them), then how could he/she face Allah on The Day of Resurrection!?
It is incumbent on your husband to seek sincere repentance from Allah for committing such a major grave sin, and fast the whole Ramadan of the coming year.
He is also obliged to immediately make up for the days that he missed because he had no lawful excuse for doing that.
Muslim scholars have made it clear that delaying making up for the missed fasting days until the start of the next Ramadan entails a ransom which is feeding one needy Muslim for each missed day, and making up for that day. Moreover, if he delayed making up for the missed fasting days until another Ramadan started, then he is to pay a new ransom; feeding one needy Muslim for each missed day.
Accordingly, your husband should estimate the ransom due on him in line with the aforesaid method.
*He should figure out the number of years in which he delayed making up for the missed fasts, and give (600 gr.) of rice, or half a JD for each missed day to the poor and needy Muslims. And Allah The Almighty Knows Best.