§ 39-21-107 — Limitations

(1) Except as provided in this section, section 29-2-208 (2)(a)(III), and section 29-2-302 (5)(b), and unless such time is extended by
waiver, the amount of any tax or of any charge on oil and gas production, and the
penalty and interest applicable to the tax or charge, shall be assessed within three
years after the return was filed, whether or not such return was filed on or after the
date prescribed, and no assessment shall be made or credit taken and no notice of
lien shall be filed, nor distraint warrant issued, nor suit for collection instituted, nor
any other action to collect the same commenced after the expiration of such period;
except that a written proposed adjustment of the tax liability by the department
issued prior to the expiration of such period shall extend the limitation of this
subsection (1) for one year after a final determination or assessment is made. No
lien shall continue after the three-year period provided for in this subsection (1),
except for taxes assessed before the expiration of such period, notice of lien with
respect to which has been filed prior to the expiration of such period, and except for
taxes on which written notice of any proposed adjustment of the tax liability has
been sent to the taxpayer during such three-year period, in which case the lien shall
continue for one year only after the expiration of such period or after the issuance
of a final determination or assessment based on the proposed adjustment issued
prior to the expiration of the three-year period. This subsection (1) does not apply to
income tax or to any tax imposed under article 23.5 of this title 39.

(2) In the case of an income tax imposed by article 22 of this title 39, unless
such time is extended by waiver and except as provided in subsection (2.5) of this
section, section 39-22-601 (6)(e), and section 39-22-601.5, the assessment of any
tax, penalties, and interest shall be made within one year after the expiration of the
time provided for assessing a deficiency in federal income tax or changing the
reported federal taxable income of a partnership, limited liability company, or
fiduciary; except that a written proposed adjustment of the tax liability by the
department must extend the limitation of this subsection (2) for one year after a
final determination or assessment is made. An assessment of income taxes having
been made according to law must be good and valid and collection thereof may be
enforced at any time within six years from the date of said assessment.

(2.5) Any limitations applicable to taxes, penalties, interest, fines, or charges
within the scope of this article 21, as set forth in section 39-21-102, are suspended:

(a) For any period during which the taxpayer's assets are in the control or
custody of a court in any proceeding before any court of the United States or any
state, and for six months thereafter; or

(b) For any period during which the department is prohibited from collecting
by reason of a case under title 11 of the United States Code, and for six months
thereafter.

(3) For purposes of this section, a tax return filed before the last day
prescribed by law or by regulation promulgated pursuant to law for the filing
thereof shall be considered as filed on such last day.

(4) In the case of failure to file a return or the filing of a false or fraudulent
return with intent to evade tax, the tax may be assessed and collected at any time.

(5) Where, before the expiration of the time prescribed in this section for the
assessment of tax, both the executive director of the department of revenue or his
delegate and the taxpayer have consented in writing to an assessment after such
time, the tax may be assessed at any time prior to the expiration of the period
agreed upon. The period so agreed upon may be extended by subsequent
agreements in writing made before the expiration of the period previously agreed
upon.

(6) Nothing in this section shall be construed to limit any right accrued or
revive any liability barred by any statute enacted on or before July 1, 1965.

Legislative History

Source: L. 65: p. 1136, � 2. C.R.S. 1963: � 138-9-6. L. 73: p. 1417, � 102. L. 77: (2) amended, p. 1770, � 1, effective May 18; (1) amended, pp. 1767, 1853, �� 4, 6, effective January 1, 1978. L. 79: (1) amended, p. 1500, � 23, effective January 1, 1980. L. 83: (1) and (2) amended, p. 1510, � 1, effective May 26. L. 86: (1) amended, p. 1110, � 6, effective July 1. L. 89: (1) amended, p. 1594, � 7, effective July 1, 1993. L. 90: (2) amended, p. 450, � 29, effective April 18; (1) amended, p. 1722, � 7, effective May 1; (1) amended, p. 1723, � 8, effective July 1, 1993. L. 92: (1) amended, p. 2247, � 1, effective July 1. L. 2001: (1) amended, p. 778, � 10, effective June 1. L. 2002: (1) amended, p. 1361, � 16, effective July 1. L. 2009: (1) amended, (HB 09-1053), ch. 159, p. 690, � 13, effective August 5. L. 2017: (1) amended, (SB 17-112), ch. 144, p. 483, � 3, effective April 18. L. 2019: (2) amended and (2.5) added, (SB 19-035), ch. 64, p. 230, � 1, effective August 2. L. 2023: (2) amended, (SB 23-1277), ch. 290, p. 1754, � 4, effective August 7. L. 2024: (1) amended, (SB 24-230), ch. 184, p. 1023, � 8, effective May 16; (1) amended, (SB 24-025), ch. 144, p. 579, � 39, effective July 1, 2025; (1) amended, (HB 24-1349), ch. 423, p. 2902, � 10, effective (see editor's note).