1. (a) If amounts are collected as tax in transactions on which tax is not due, the comptroller will require, under the doctrine of unjust enrichment, that these amounts be remitted to the state or be refunded to the customers from whom they were collected.
2. (b) In the case of refunded amounts, documentary evidence must be retained establishing the transaction, the amount collected, the party from whom collected, the amount refunded, and the party to whom refund is made.

Source Note:The provisions of this §3.3 adopted to be effective January 1, 1976.