The general rule is at the Federal Level, seven years, and at The State Level, nine years. This amount of time is calculated from the filing date of the return, rather than the year. However, if the authorities can prove fraud, they can go back as many years as they want. It’s a terrible burden on any business. Don’t get rid of your records. If you are asking this question in the first place, then it’s probably time for a new accountant.