S3 E30 Dogs, Dogs, Dogs we learn Andy pays for Otis's meals out of his own pocket. Inspector Somerset does agree into the episode for more funding. It isn't mentioned if prisoner food money will be included as Barney hoped for. Let's assume it is.

But, it raises the question how about all the other prisoners in now close to 3 years. If Andy is playing for Otis's food I assume he pays for all prisoners meals. Adds up over 3 years on not a generous salary I'm sure.

I guess he could feed them Aunt Bee's pickles but that'd be cruel and unusual punishment.

Andy was a generous guy. In addition to providing breakfast for Otis, he had Aunt Bee cook dinner for the entire Darling family at least a couple times, and also for Jim Lindsey. And Andy invited Gomer to stay at his house after Wally fired him. I wonder what Aunt Bee thought about Andy's generosity?

The president of the united states used to pay for state dinners personally until the debt became a hardship. perhaps it's along the same vein.

Maybe Andy's skimming a little off the top of whatever Thelma Lou and the Fun girls do to support themselves? Since we know Andy feels entitled to bend/break the rules so long as it's for a noble cause, that certainly looks like a possibility.