What is the statute of limitations for IRS audits and amended returns?

The IRS generally has three years from the filing date to audit your return and assess additional tax. That window extends to six years if you under-reported income by more than 25% and has no limit if the IRS suspects fraud or you never filed. You also have three years from the original due date to file an amended return claiming a refund. Keeping records for at least seven years is a safe rule of thumb.