(a) Paragraph (1) of section 1312 applies if the determination requires the inclusion in a taxpayer's gross income of an item which was erroneously included in the gross income of the same taxpayer for another taxable year or of 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 who keeps his books on the cash method erroneously included in income on his return for 1947 an item of accrued rent. In 1952, after the period of limitation on refunds for 1947 had expired, the Commissioner discovered that the taxpayer received this rent in 1948 and asserted a deficiency for the year 1948 which is sustained by the Tax Court of the United States in 1955. An adjustment in favor of the taxpayer is authorized with respect to the year 1947. If the taxpayer had returned the rent for both 1947 and 1948 and by a determination was denied a refund claim for 1948 on account of the rent item, a similar adjustment is authorized. Example 2.A husband assigned to his wife salary to be earned by him in the year 1952. The wife included such salary in her separate return for that year and the husband omitted it. The Commissioner asserted a deficiency against the wife for 1952 with respect to a different item; she contested that deficiency, and the Tax Court entered an order in her case which became final in 1955. The wife would therefore be barred by section 6512(a) from claiming a refund for 1952. Thereafter, the Commissioner asserted a deficiency against the husband on account of the omission of such salary from his return for 1952. In 1955 the husband and the Commissioner enter into a closing agreement for the year 1952 in which the salary is taxed to the husband. An adjustment is authorized with respect to the wife's tax for 1952. [T.D. 6500, 25 FR 12033, Nov. 26, 1960]