§ 301.6501(m)-1 Tentative carryback adjustment assessment period.
(a) Period of limitation after tentative carryback adjustment.
(1) Under section 6501(m), in a case where an amount has been applied, credited, or refunded under section 6411, by reason of a net operating loss carryback, a capital loss carryback, an investment credit carryback, or a work incentive program credit carryback to a prior taxable year, the period described in section 6501(a) of the Code for assessing a deficiency for such prior taxable year is extended to include the period described in section 6501 (h), (j), or (o), whichever is applicable; except that the amount which may be assessed solely by reason of section 6501(m) may not exceed the amount so applied, credited, or refunded under section 6411, reduced by any amount which may be assessed solely by reason of section 6501 (h), (j), or (o), as the case may be.
(2) The application of this paragraph may be illustrated by the following example:
Assume that M Corporation, which claims an unused investment credit of $50,000 for the calendar year 1968, files an application under section 6411 of the Code for an adjustment of its tax for 1965, and receives a refund of $50,000 in 1969. In 1971, it is determined that the amount of the unused investment credit for 1968 is $30,000 rather than $50,000. Moreover, it is determined that M Corporation would have owed $40,000 of additional tax for 1965 if it had properly reported certain income which it failed to include in its 1965 return. Assuming that M Corporation filed its 1968 return on March 15, 1969, and that the 3-year period described in section 6501(a) has not been extended, the period prescribed in section 6501(j) for assessing the excessive amount refunded, $20,000 (i.e., $50,000, original amount refunded less $30,000, correct amount of unused investment credit), does not expire until March 15, 1972, and $20,000 may be assessed on or before such date under section 6501(j). Under section 6501(m), M Corporation may be assessed on or before March 15, 1972, an amount not in excess of $30,000 ($50,000, the amount refunded under section 6411, minus $20,000, the amount which may be assessed solely by reason of section 6501 (j)).
(b) Effective date. The provisions of paragraph (a) of this section apply only with respect to applications under section 6411 filed after November 2, 1966.