The law says that you can always claim up to two years of past unpaid overtime pay. If the employer’s failure to pay overtime under the law is determined to be “willful” – generally meaning that the employer knew or should have known they were violating the overtime laws – then you can claim an additional 3rd year of overtime pay. Keep in mind, though, that the clock only stops running when you actually filed your claim. So if you have unpaid overtime pay going back two and perhaps three years, every week that you fail to take action may be a week of unpaid overtime pay that is lost forever.