Q: Assalamualakem Imam, if a person missed fasts from last Ramadan due to sickness, can they make it up anytime? Does it have to be before next ramadan?
What if the person is still sick or don’t have strength and are weak? Can they make it up anytime?

A: Walaikumsalam:

May Allah (SAW) reward you for your concern about fasting.

Making Up Missed Fasts

The general rule is that missed fasts due to illness should be made up as soon as one is physically able.

You can make them up anytime throughout the year. However, it is highly recommended to complete them before the next Ramadan begins.

If the next Ramadan arrives and you still have not made up the previous year’s fasts without a valid excuse (like an ongoing illness), you still owe those fasts, so try and make it up as soon as possible. 

If Illness or Weakness Persists

 If you are still recovering but expect to get better eventually, you simply can wait until you have the strength. 

Chronic/Permanent Illness: If a good (Moreso, Muslim doctor that knows this aspect of religion) doctor determines the condition is chronic and the person will likely never be strong enough to fast again, they do not have to make up the days. Instead, they pay Fidya. If you do ever recover, even after you have paid the fidya, you would still do a makeup due to recovery.

Fidya: Feeding one poor person a meal for every day missed. Or you could give its equivalent in money to the poor person. (If a meal cost $10, and you missed 12 fasts, give the poor person $120)

Allah Certainly Knows Best.