(a) Noncorporate obligations—(1) Deductible as bad debt. A payment during the taxable year by a taxpayer other than a corporation in discharge of part or all of his obligation as a guarantor, endorser, or indemnitor of an obligation issued by a person other than a corporation shall, for purposes of section 166 and the regulations thereunder, be treated as a debt's becoming worthless within the taxable year, if—
(i) The proceeds of the obligation so issued have been used in the trade or business of the borrower, and
(ii) The borrower's obligation to the person to whom the taxpayer's payment is made is worthless at the time of payment except for the existence of the guaranty, endorsement, or indemnity, whether or not such obligation has in fact become worthless within the taxable year in which payment is made.
(2) Nonbusiness debt rule not applicable. If a payment is treated as a loss in accordance with the provisions of subparagraph (1) of this paragraph, section 166(d), relating to the special rule for losses sustained on the worthlessness of a nonbusiness debt, shall not apply. Accordingly, in each instance the loss shall be deducted under section 166(a)(1) as a wholly worthless debt even though there has been a discharge of only a part of the taxpayer's obligation. Thus, if the taxpayer makes a payment during the taxable year in discharge of only part of his obligation as a guarantor, endorser, or indemnitor, he may treat such payment under section 166(a)(1) as a debt's becoming wholly worthless within the taxable year, provided that he can establish that such part of the borrower's obligation to the person to whom the taxpayer's payment is made is worthless at the time of payment and the conditions of subparagraph (1) of this paragraph have otherwise been satisfied.
(3) Other applicable provisions. Other provisions of the internal revenue laws relating to bad debts, such as section 111, relating to the recovery of bad debts, shall be deemed to apply to any payment which, under the provisions of this paragraph, is treated as a bad debt. If the requirements of section 166(f) are not met, any loss sustained by a guarantor, endorser, or indemnitor upon the worthlessness of the debtor's obligation shall be treated under the provisions of law applicable thereto. See, for example, paragraph (b) of this section.
(b) Corporate obligations. The loss sustained during the taxable year by a taxpayer other than a corporation in discharge of all of his obligation as a guarantor of an obligation issued by a corporation shall be treated, in accordance with section 166(d) and the regulations thereunder, as a loss sustained on the worthlessness of a nonbusiness debt if the debt created in the guarantor's favor as a result of the payment does not come within the exceptions prescribed by section 166(d)(2) (A) or (B). See paragraph (a)(2) of §1.166-5.
(c) Examples. The application of this section may be illustrated by the following examples:
(d) Effective date. This section applies only to losses, regardless of the taxable year in which incurred, on agreements made before January 1, 1976.
[T.D. 6500, 25 FR 11402, Nov. 26, 1960, as amended by T.D. 7657, 44 FR 68464, Nov. 29, 1979]