# Pub. L. 89-721: changes to the Internal Revenue Code 1966-11-02, 80 Stat. 1150. Source: . ## Legislative history - Bill: [H.R. 11660](https://www.congress.gov/bill/89th-congress/house-bill/11660) ## § 6411: Tentative carryback and refund adjustments - § 6411(a): Pub. L. 89–721, § 2(a)–(c), provided in introductory text for a tentative carryback adjustment based on an investment credit carryback as provided for in section 46(b) of this title and inserted “or unused investment credit” after “the taxable year of the net operating loss”, inserted in par. (1) “or unused investment” after “net operating loss”, and struck out in par. (5) “of such loss” and inserted in lieu thereof “from which the carryback is made”. - § 6411(b): Pub. L. 89–721, § 2(d), inserted “or unused investment credit” after “net operating loss” in two places. - § 6411(c): Pub. L. 89–721, § 2(d), (e), inserted “or unused investment credit” after “net operating loss” and “or credit” after “such loss”. ## § 6501: Limitations on assessment and collection - § 6501(j): Pub. L. 89–721, § 2(f), substituted “investment credit carryback (including deficiencies which may be assessed pursuant to the provisions of section 6213(b)(2))” for “investment credit carryback”. - § 6501(m): Pub. L. 89–721, § 3(a), added subsec. (m). ## § 6611: Interest on overpayments - § 6611(e): Pub. L. 89–721 inserted “or, in case the return is filed after such last date, is refunded within 45 days after the date the return is filed” after “(determined without regard to any extension of time for filing the return)” and changed heading to reflect amendment.