How many years back can I file?

[LeonardS]

3 years is the statute of limitations to claim a refund.

If you are due a refund for withholding or estimated taxes, you must file your return to claim it within 3 years of the return due date. The same rule applies to a right to claim tax credits such as the Earned Income Credit.

6 years is the time period to file tax returns for years in which you did not file.

IRS Policy Statement 5-133, Delinquent Returns – Enforcement of Filing Requirements, provides a general rule that taxpayers must file six years of back tax returns to be in good standing with the IRS. The policy also states that IRS management would have to approve any deviation from that rule.