A statute of limitation is the time period established by law during when IRS can review, analyze, and resolve your tax-related issues. When the statutory period expires, we can no longer assess or collect additional tax, or allow you to claim a refund. Statute expiration dates The expiration date of a statute of limitation depends on the: Time IRS can assess tax Time IRS can collect tax Time you can claim a credit or refund How to know which statute expiration date applies to you When we assess or collect taxes from you or when we decide on your filed claim for a credit or refund, we mail you a notice or letter. The notice or letter will tell you about the tax year, what actions we're taking and next steps. For more information, see Understanding your notice or letter. Laws IRC 6501 IRC 6502 IRC 6511