If you have social security income are not required to file federal income tax returns do you have to file to receive the 2008 rebate?

Yes. There may be a way to get it by filing next year, but I wouldn't count on it. Efile your return this year to get the stimulus money by May. There are special stimulus returns, and I think there is free online filing. Some tax places are doing these returns for 30 or 40 bucks if you prefer. CH, 5 years in the tax bus.