(a)(1) As used in this subsection, the term "return allowance" means the amount of the sales price or cost price refunded by the dealer to the purchaser in cash or credit. No credit shall be allowed to the dealer under this subsection for taxes collected by him from the purchaser unless the taxes collected have been returned by him to the purchaser.

(2) When property sold is subsequently returned by agreement to the dealer by the purchaser, the dealer shall be entitled to credit for the tax imposed by this article with respect to the return allowance, in the manner prescribed by the commissioner, as follows:

(A) If property is returned within 90 days from the date of sale, the dealer in his original return for the taxable period in which the return of the property is allowed by him may deduct from his gross sales the amount of the return allowance;

(B) If property is returned more than 90 days from the date of sale, no credit shall be allowed except upon application for a credit memorandum in the amount of the tax imposed with respect to the return allowance. The application shall be made and the credit memorandum issued in the manner prescribed by the commissioner. The application shall be made within the time provided by law for the filing of claims for refund. The credit memorandum shall be applied by the dealer to his liability for each succeeding taxable period until exhausted; or

(C) When a dealer has retired from business and has filed a final return, a claim for refund of the tax for which the dealer would be entitled to credit under this subsection may be filed within the time and in the manner prescribed by law.

(b) The commissioner shall make available to dealers all necessary forms for filing returns and instructions to ensure a full collection from dealers and an accounting for the taxes due. Failure of any dealer to secure the commissioner's forms shall not relieve the dealer from the payment of the tax at the time and in the manner provided in this article.