Keep your resale records for five years.
Washington sellers who skip sales tax on a reseller permit need the proof on file. The Department of Revenue says to keep the documentation for five years, because an exempt sale without proof is a taxable sale.
Transcript
Sal When you sell without charging sales tax because the buyer gave you a reseller permit, you have to be able to prove it. Washington's Department of Revenue says to keep the documentation for five years. An exempt sale without proof is a taxable sale.