I have three frozen containers of schmaltz. The newest is three months old; the oldest is probably a couple of years old. Are any of them edible?
It definitely depends on the kind of schmaltz you are having, but to be honest I never have seen schmaltz gone bad, even after several years. I have had schmaltz in the fridge for over a year and it was still perfectly fine.
I'd suggest the following: follow your gut. Just look at it and check for the usual signs. In order: Does it look normal (no mold, no discoloration, normal consistency)? Does it smell normal? Does it taste normal? Then it's probably still good and you can use it for whatever you like. If you're still unsure: use it for cooking only.
I'm not certain about the older ones, but frozen schmaltz should be fine for a while, at least a few months.