There is a very good reason to keep a hold of past tax returns and associated documents as they can come in very handy in the event that the Internal Revenue Service decides to question any of the entries on your old tax returns. The IRS usually has no more than three years after the filing of a tax return to file an audit in most instances, but while this means you should definitely keep tax returns of up to three years old, it does not mean you should just throw out old ones.
If you have any concerns at all that the IRS might want to see those returns at a later date and that you might be vulnerable to being audited, you should keep those returns. The IRS can audit returns from as far back as six years if they suspect you have been under-reporting your income by a minimum of twenty five percent. It can even go back indefinitely if they suspect that deliberate fraud has been committed. A copy can be retrieved on the IRS’ own website if filed electronically, but the best call would be to consider that only a back-up and make sure you keep your own.