HOW LONG IS LONG ENOUGH?
Federal law requires you to maintain copies of your tax returns and supporting documents for three years. This is called the “three-year law” and leads many people to believe they’re safe provided they retain their documents for this period of time.
However, if the IRS believes you have significantly under reported your income (by 25 percent or more) or believes there may be indication of fraud, it may go back six years in an audit. To be safe, use the following guidelines.