280-20-70 R.I. Code R. § 28.19
When a used car dealer or auto body repairer holding a motor vehicle dealer's license and permit to make sales at retail purchases a new motor vehicle from a new car dealer such used car dealer or auto body repair shall be deemed liable for the payment of tax thereon unless such used car dealer or auto body repairer can show, by proper records, that the motor vehicle in question was actually purchased for resale in which case the tax shall not apply; provided, however, when the used car dealer or auto body repairer sells the motor vehicle in question within thirty (30) days of its purchase from the new car dealer it shall be presumed that such used car dealer or auto body repairer purchased the motor vehicle for resale.
280 R.I. Code R. § 280-RICR-20-70-28.19