1998—Subsec. (a). Pub. L. 105–206, § 3461(a)(2), struck out first sentence of concluding provisions which read as follows: “The period so agreed upon may be extended by subsequent agreements in writing made before the expiration of the period previously agreed upon.”

Subsec. (a)(2). Pub. L. 105–206, § 3461(a)(1), added par. (2) and struck out former par. (2) which read as follows: “prior to the expiration of any period for collection agreed upon in writing by the Secretary and the taxpayer before the expiration of such 10-year period (or, if there is a release of levy under section 6343 after such 10-year period, then before such release).”

1990—Subsec. (a)(1). Pub. L. 101–508, § 11317(a)(1), substituted “10 years” for “6 years”.

Subsec. (a)(2). Pub. L. 101–508, § 11317(a)(2), substituted “10-year period” for “6-year period” wherever appearing.

1989—Subsec. (a). Pub. L. 101–239 substituted “unenforceable” for “enforceable” in last sentence.

1988—Subsec. (a). Pub. L. 100–647 amended last sentence generally. Prior to amendment, last sentence read as follows: “The period provided by this subsection during which a tax may be collected by levy shall not be extended or curtailed by reason of a judgment against the taxpayer.”

1976—Subsec. (a)(2). Pub. L. 94–455 struck out “or his delegate” after “Secretary”.

1966—Subsec. (a). Pub. L. 89–719 inserted sentence at end providing that the period provided by this subsection during which a tax may be collected by levy shall not be extended or curtailed by reason of a judgment against the taxpayer.

Amendments by Pub. L. 105–206 applicable to requests to extend period of limitations made after Dec. 31, 1999, with special provisions relating to requests made on or before such date, see section 3461(c) of Pub. L. 105–206, set out as a note under section 6501 of this title.

Amendment by Pub. L. 101–508 applicable to taxes assessed after Nov. 5, 1990, and to taxes assessed on or before that date if the period specified in this section (determined without regard to the amendments made by Pub. L. 101–508) for collection of such taxes has not expired as of such date, see section 11317(c) of Pub. L. 101–508, set out as a note under section 6323 of this title.

Amendment by Pub. L. 101–239 effective, except as otherwise provided, as if included in the provision of the Technical and Miscellaneous Revenue Act of 1988, Pub. L. 100–647, to which such amendment relates, see section 7817 of Pub. L. 101–239, set out as a note under section 1 of this title.

Pub. L. 100–647, title I, § 1015(u)(2), Nov. 10, 1988, 102 Stat. 3573, provided that: “The amendment made by this subsection [amending this section] shall apply to levies issued after the date of the enactment of this Act [Nov. 10, 1988].”

Amendment by Pub. L. 89–719 applicable after Nov. 2, 1966, regardless of when title or lien of United States arose or when lien or interest of another person was acquired, except in a case in which a lien or title derived from enforcement of a lien held by United States has been enforced by a civil action or suit which has become final by judgment, sale, or agreement before Nov. 2, 1966, or in a case in which the amendment would impair a priority held by any person other than United States holding a lien or interest prior to Nov. 2, 1966, operate to increase liability of such person, or shorten the time for bringing suit with respect to transactions occurring before Nov. 2, 1966, see section 114(a)–(c) of Pub. L. 89–719, set out as a note under section 6323 of this title.