1.    Taxes paid on gross receipts represented by accounts found to be worthless and actually charged off for income tax purposes may be credited upon subsequent payment of the tax herein provided; provided, that if such accounts are hereafter collected by the retailer, a tax must be paid upon the amount so collected. If a retailer’s filing responsibility has been assumed by a certified service provider, the certified provider may claim on behalf of the retailer any bad debt allowance provided under this section. The certified service provider shall credit or refund to the retailer the full amount of any bad debt allowance or refund received under this section.

2.    If a retailer has remitted the sales tax due on the full amount of an installment sales contract rather than on only the installment payments received, the retailer may deduct as a credit against the retailer’s sales tax liability on the next return that the retailer is required to file the amount of sales tax the retailer paid on the installment contract payments which were not made by the purchaser of the merchandise sold under such contract; such credit may be deducted by the retailer regardless of whether or not said retailer has assigned the contract, provided, however, that if the retailer has assigned the contract the retailer must have assigned it subject to an agreement to repurchase the contract in the event of default by the purchaser under the contract or subject to a guarantee that the payments under the contract would be made. In the event such deduction exceeds the amount of sales tax due the state by the retailer in the next regular return, such excess must be allowed as credit against future sales tax due from the retailer. If in any case the credit, or any part of it, cannot be utilized by the retailer because of a discontinuance of a business or for other valid reasons, the amount thereof may be refunded to the retailer.