(a) Paragraph (2) of section 1312 applies if the determination allows the taxpayer a deduction or credit which was erroneously allowed the same taxpayer for another taxable year or a related taxpayer for the same or another taxable year.

(b) The application of paragraph (a) of this section may be illustrated by the following examples:

Example 1.A taxpayer in his return for 1950 claimed and was allowed a deduction for destruction of timber by a forest fire. Subsequently, it was discovered that the forest fire occurred in 1951 rather than 1950. After the expiration of the period of limitations for the assessment of a deficiency for 1950, the taxpayer filed a claim for refund for 1951 based upon a deduction for the fire loss in that year. The Commissioner in 1955 allows the claim for refund. An adjustment is authorized with respect to the year 1950. Example 2.The beneficiary of a testamentary trust in his return for 1949 claimed, and was allowed, a deduction for depreciation of the trust property. The Commissioner asserted a deficiency against the beneficiary for 1949 with respect to a different item and a final decision of the Tax Court of the United States was rendered in 1951, so that the Commissioner was thereafter barred by section 272(f) of the Internal Revenue Code of 1939 from asserting a further deficiency against the beneficiary for 1949. The trustee thereafter filed a timely refund claim contending that, under the terms of the will, the trust, and not the beneficiary, was entitled to the allowance for depreciation. The court in 1955 sustains the refund claim. An adjustment is authorized with respect to the beneficiary's tax for 1949. [T.D. 6500, 25 FR 12033, Nov. 26, 1960]