Tax records should be kept year-round, not hastily assembled just for your annual tax appointment. Without tax records, you can lose valuable deductions by forgetting to list expenses on your return or having unsubstantiated items disallowed if you’re audited.
Generally returns can be audited up to three years after filing. However, if income is underreported by more than 25%, the Internal Revenue Service can collect underpaid taxes up to six years later. In other words, you need good records to verify what you report on your tax return, and you should hang on to those records for seven years.