How Long Should I Keep Tax Records?
You must keep your records for as long as they are important to federal and state tax law. For most cases that is 3 years from when the return is filed, or 2 years from when the tax is paid, whichever is later.
Most states expect you keep them longer so you should add on another year to cover that. The statute of limitations is longer still if you materially understate your income.
Certain records relating to costs should be kept as long as you own the asset. Examples of these types of assets are: Personal residences (improvements too), Stock and mutual fund costs (after tax accounts), investment and rental real estate, and business assets.