Sales and Use Tax Records (Publication 116)
Retaining Records

You should keep required records for at least four years unless we give you specific, written authorization to destroy them sooner.

If you are being audited, retain all records that cover the audit period until the audit is complete, even if that means keeping them longer than four years. In addition, if you have a dispute with us about how much tax you owe, it is important to retain the related records until that dispute is resolved. For instance, if you appeal the results of an audit or another determination (billing), or file a claim for refund, keep your records while that matter is pending.

If you have a point-of-sale system that overwrites data after a period of time less than four years, you should transfer, maintain, and have available, all data that would have been overwritten or otherwise removed from the system for the required time periods indicated above.