In California, you have to file your claim for unpaid wages within three years of the unpaid overtime you earned (or four years if you file in civil court and add a claim for violation of California Business and Professions Code section 17200). Here’s an example:
Jim works for a company for five years. The company never paid Jim overtime that he earned. Jim files his claim for unpaid wages with the California Labor Commissioner (a three year statute of limitations) on July 1, 2011. He can reclaim the unpaid overtime wages going back to July 1, 2008. Any unpaid overtime he earned before then would be beyond his reach in his wage claim, unless he filed in civil court and added the California Business and Professions Code section 17200 claim, which would allow him to reach back to July 1, 2011 for his unpaid overtime.