According to the USDA, whole chicken can be used for up to 12 months, and chicken parts can be used for up to 9 months. The state that these guidelines are for "quality" only- that the chicken will stay safe to use indefinitely if stored at 0 degrees Farenheit..

From personal experience (and not what the FDA or USDA says) I've had chicken that still tasted fine at over two years. A friend of mine who raises chickens didn't sell them all at the farmer's market one fall a few years ago. When farmers are raising pastured chickens for the farmer's markets, they usually process them all within a short time-frame in the fall. He did this and the weather turned so that people didn't come to the market, and he ended up with several dozen more chickens than his own family could use.

The next spring when the market opened again, the chickens had then been in the freezer for 7 months, and he was afraid that if any of them weren't perfect his reputation would suffer. He had 17 left and gave them all to me.

For the next 6-8 months, every single one we had was fine. By the end of that time they were 15 months frozen. After that, most were ok, but we had two that tasted "old". We promptly turned them into soup with lots of garlic and onion, and they were fine. We ate the last one when it had to be over 2 years since it had been frozen, and it was one that tasted fine.

This is anecdotal, but most people have never had a large supply of chickens raised the same way and frozen at the same time to test.