SDCL § 10-33A-14: Uncollectible debts may be deducted from gross receipts--Subsequent collection subject to tax.

Any refund or allowance made by any telecommunication service or any amount written off the books of a telecommunications company reporting financial information on an accrual basis may be reported as an uncollectible debt and deducted from the gross receipts of any telecommunications service. If any uncollectible debt is subsequently collected, the amount is subject to the telecommunications gross receipts tax and shall be reported to the department in the month of collection.