Article took from Worship

Question: Concerning the one who had days to make up from the previous Ramadhaan and had not done so when the following Ramadhaan arrived, is he a sinner and does he have to make an expiation or not?

Response: Anyone who has days to make up from the (previous) Ramadhaan then he has to make them up before (the arrival of) the next Ramadhaan. It is permissible for him to delay his fast until Sha'baan (the 8th month, just before Ramadhaan). However, if the following Ramadhaan arrives and he still has not made up the (missed) days without (a valid) reason, then he has committed a sin. So now he has to make up those days along with feeding a poor person for every day (he has to make up) as this is what the group of companions of the Prophet (sal-Allaahu `alayhe wa sallam) had ruled with. The amount of food required would be half a saa'a for every day from that which is the norm in the country and is to be given to a number of people or, even, just one person. As for he who had a valid excuse for delaying in making up the fasts, because of illness or travel then he has to make up the days missed only and he does not have to feed any poor people, for the general statement of Allaah (subhaanahu wa ta'aala): {and whoever is ill or on a journey, the same number (of days which one did not fast must be made up) from other days} [Soorah al-Baqarah, Aayah 185].

And Allaah (subhaanahu wa ta'aala) is the Provider of Success.

Shaykh Ibn Baaz
Fataawa Ramadhaan - Volume 2, Page 555, Fatwa No. 537;
al-Fataawa libni-Baaz - Kitaab ad-Da'waah, Volume 2, Page 158-159