CO Code § 39-21-108 (2021)
2021 Colorado Code|Title 39 - Taxation|Article 21 - Procedure and Administration|Part 1 - General Provisions|§ 39-21-108. Refunds

     In the case of income tax imposed by article 22 of this title, the taxpayer must file any claim for refund or credit for any year not later than the period provided for filing a claim for refund of federal income tax plus one year. However, any extensions of the period by agreement between the taxpayer and the federal taxing authorities shall extend the period established in this section by the same amount of time. The department shall not pay any refund for which the claim is filed later than the period provided for the payment of a refund of federal income tax plus one year. However, no refund or credit of income tax shall be made to any taxpayer who fails to file a return pursuant to section 39-22-601 within four years from the date the return was required to be filed. Except in the case of failure to file a return or the filing of a false or fraudulent return with intent to evade tax and otherwise notwithstanding any provision of law, the statute of limitations relating to claims for refund or credit for any year shall not expire prior to the expiration of the time within which a deficiency for such year could be assessed. In the case of the charge on oil and gas production imposed by article 60 of title 34, C.R.S., and the passenger-mile tax imposed by article 3 of title 42, C.R.S., or the severance tax imposed by article 29 of this title, the taxpayer shall file any claim for refund or credit for any period not later than three years after the date of payment. Claims for refund of other taxes covered by this article shall be made within the time limits expressly provided for the specific taxes involved. Except as provided in section 39-21-105, no suit for refund may be commenced. This subsection (1) shall not apply to sales and use taxes.    Repealed.       If the executive director discovers from the examination of a return within the time periods provided for the filing of refunds, or upon claim duly filed by the taxpayer, or upon final judgment of a court that the tax, penalty, or interest paid by any taxpayer is in excess of the amount due or has been illegally or erroneously collected, then the executive director shall issue in favor of the taxpayer his voucher to the controller for the refund of such illegally collected tax, penalty, or interest, regardless of whether or not such sum was paid under protest, together with interest provided in section 39-21-110. Upon receipt of such voucher properly executed and endorsed, the controller shall issue his warrant for the payment to the taxpayer out of the reserve provided therefor; but the controller shall keep in his files a duplicate of said voucher and also a statement which shall set forth the reason why such refund has been ordered.          Whenever it is established that any taxpayer has, for any period open under the statutes, overpaid a tax covered by articles 22 and 26 to 29 of this title 39, article 60 of title 34, and article 3 of title 42 and that: There is an unpaid balance of tax and interest accrued, according to the records of the executive director, owing by such taxpayer for any other period; there is an amount required to be repaid to the unemployment compensation fund pursuant to section 8-81-101 (4), the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment by the division of unemployment insurance in the department of labor and employment; there is any unpaid child support debt as set forth in section 14-14-104, or child support arrearages that are the subject of enforcement services provided pursuant to section 26-13-106, as certified by the department of human services; there are any unpaid obligations owing to the state as set forth in section 26-2-133, for overpayment of public assistance or medical assistance benefits, the amount of which has been determined to be owing as a result of final agency determination or judicial decision or that has been reduced to judgment, as certified by the department of human services; there is any unpaid loan or other obligation due to a state-supported institution of higher education as set forth in section 23-5-115, the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment, as certified by the appropriate institution; there is any unpaid loan due to the student loan division of the department of higher education as set forth in section 23-3.1-104 (1)(p), the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment, as certified by the division; there is any unpaid loan due to the collegeinvest division of the department of higher education as set forth in section 23-3.1-206, the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment; there is any outstanding judicial fine, fee, cost, or surcharge as set forth in section 16-11-101.8, or judicial restitution as set forth in section 16-18.5-106.8, the amount of which has been determined to be owing as a result of a final judicial department determination or certified by the judicial department as a judgment owed the state or a victim; there is any unpaid debt owing to the state or any agency thereof by such taxpayer, and that is found to be owing as a result of a final agency determination or the amount of which has been reduced to judgment and as certified by the state agency; or the taxpayer is a qualified individual identified pursuant to section 39-22-120 (10) or 39-22-2003 (9), so much of the overpayment of tax plus interest allowable thereon as does not exceed the amount of such unpaid balance or unpaid debt must be credited first to the unpaid balance of tax and interest accrued and then to the unpaid debt, and any excess of the overpayment must be refunded. If the taxpayer elects to designate his or her refund as a credit against a subsequent year's tax liability, the amount allowed to be so credited must be reduced first by the unpaid balance of tax and interest accrued and then by the unpaid debt. If the taxpayer filed a joint return, the executive director shall notify the other taxpayer named on the joint return that the portion of the overpayment that is generated by the other taxpayer's income will be refunded upon receipt of a request detailing said amount. (a) (I) (A) Whenever it is established that any taxpayer has, for any period open under the statutes, overpaid a tax covered by articles 22 and 26 to 29 of this title 39, article 60 of title 34, and article 3 of title 42 and that: There is an unpaid balance of tax and interest accrued, according to the records of the executive director, owing by such taxpayer for any other period; there is an amount required to be repaid to the unemployment compensation fund pursuant to section 8-81-101 (4), the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment by the division of unemployment insurance in the department of labor and employment; there is any unpaid child support debt as set forth in section 14-14-104, or child support arrearages that are the subject of enforcement services provided pursuant to section 26-13-106, as certified by the department of human services; there are any unpaid obligations owing to the state as set forth in section 26-2-133, for overpayment of public assistance or medical assistance benefits, the amount of which has been determined to be owing as a result of final agency determination or judicial decision or that has been reduced to judgment, as certified by the department of human services; there is any unpaid loan or other obligation due to a state-supported institution of higher education as set forth in section 23-5-115, the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment, as certified by the appropriate institution; there is any unpaid loan due to the student loan division of the department of higher education as set forth in section 23-3.1-104 (1)(p), the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment, as certified by the division; there is any unpaid loan due to the collegeinvest division of the department of higher education as set forth in section 23-3.1-206, the amount of which has been determined to be owing as a result of a final agency determination or judicial decision or that has been reduced to judgment; there is any outstanding judicial fine, fee, cost, or surcharge as set forth in section 16-11-101.8, or judicial restitution as set forth in section 16-18.5-106.8, the amount of which has been determined to be owing as a result of a final judicial department determination or certified by the judicial department as a judgment owed the state or a victim; there is any unpaid debt owing to the state or any agency thereof by such taxpayer, and that is found to be owing as a result of a final agency determination or the amount of which has been reduced to judgment and as certified by the state agency; or the taxpayer is a qualified individual identified pursuant to section 39-22-120 (10) or 39-22-2003 (9), so much of the overpayment of tax plus interest allowable thereon as does not exceed the amount of such unpaid balance or unpaid debt must be credited first to the unpaid balance of tax and interest accrued and then to the unpaid debt, and any excess of the overpayment must be refunded. If the taxpayer elects to designate his or her refund as a credit against a subsequent year's tax liability, the amount allowed to be so credited must be reduced first by the unpaid balance of tax and interest accrued and then by the unpaid debt. If the taxpayer filed a joint return, the executive director shall notify the other taxpayer named on the joint return that the portion of the overpayment that is generated by the other taxpayer's income will be refunded upon receipt of a request detailing said amount.    With respect to debts for any unpaid loan or other obligation due to a state-supported institution of higher education as set forth in section 23-5-115, C.R.S., or any unpaid loan due to the student loan division of the department of higher education as set forth in section 23-3.1-104 (1)(p), C.R.S., or any unpaid loan due to the collegeinvest division of the department of higher education as set forth in section 23-3.1-206, C.R.S., a debtor must be afforded his or her due process rights prior to a final agency determination.       Any moneys withheld for payment of an unemployment compensation benefit debt pursuant to this subsection (3) shall be deposited with the state treasurer and credited to the unemployment compensation fund. For persons required to repay benefit overpayments in accordance with section 8-81-101 (4)(a), C.R.S., the executive director of the department of revenue shall provide to said division the taxpayers' names and associated amounts deposited with the state treasurer.    Any moneys withheld for payment of a child support debt or child support arrearages pursuant to this subsection (3) shall be deposited in the family support registry created pursuant to section 26-13-114, C.R.S., for disbursement by the department of human services. For all names and amounts certified by the department of human services pursuant to section 26-13-111, C.R.S., the executive director of the department of revenue shall provide to the department of human services the taxpayers' names and associated amounts deposited with the state treasurer and any other identifying information as required by the department of human services.    Any moneys withheld for payment of an institution of higher education debt pursuant to this subsection (3) shall be deposited with the state treasurer for disbursement by the state treasurer to the appropriate institution. For each person whose name and amount is certified by the appropriate institution pursuant to section 23-5-115, C.R.S., the executive director of the department of revenue shall provide to the appropriate institution the name, address, and social security number or federal employer identification number, whichever is applicable, of the taxpayer whose refund is being offset, the amount of the offset, and any other identifying information as required by the institution.    Any money withheld for payment of an unpaid debt owing to the state pursuant to this subsection (3) shall be deposited with the state treasurer for disbursement by the controller. For each person whose name and amount is certified by a state agency pursuant to section 24-30-202.4, the executive director of the department of revenue shall provide to the controller the name, address, and social security number or federal employer identification number, whichever is applicable, of the taxpayer whose refund is being offset, the amount of the offset, and any other identifying information as required by the controller.    Any moneys withheld for payment of a student loan division debt pursuant to this subsection (3) shall be deposited with the state treasurer for disbursement by the state treasurer to the division. For each person whose name and amount is certified by the division pursuant to section 23-3.1-104 (1)(p), C.R.S., the executive director of the department of revenue shall provide to the division the name, address, and social security number or federal employer identification number, whichever is applicable, of the taxpayer whose refund is being offset, the amount of the offset, and any other identifying information as required by the division.    Any moneys withheld for payment of obligations owed the department of human services for overpayment of public assistance benefits pursuant to this subsection (3) shall be deposited with the state treasurer for disbursement by the department of human services. For all names and associated amounts certified by the department of human services pursuant to section 26-2-133, C.R.S., the executive director of the department of revenue shall provide to the department of human services the names of taxpayers and the associated amounts deposited with the state treasurer and any other identifying information as required by the department of human services.    Any moneys withheld for payment of an obligation certified by the judicial department pursuant to section 16-11-101.8 or 16-18.5-106.8, C.R.S., shall be transferred to the judicial department. At the time of the offset, the executive director shall notify the taxpayer of the offset and shall provide to the judicial department the name, address, and social security number or federal employer identification number, whichever is applicable, of the taxpayer whose refund is being offset, the amount of the offset, and any other identifying information as required by the judicial department.       In the event there are debts for overpayments of unemployment insurance pursuant to section 8-81-101 (4), C.R.S., debts for unpaid child support, as set forth in section 26-13-111, C.R.S., debts for overpayment of public assistance or medical assistance benefits, as set forth in section 26-2-133, C.R.S., debts for any unpaid loan or other obligation due to a state-supported institution of higher education, as set forth in section 23-5-115, C.R.S., debts for any unpaid loan due to the student loan division of the department of higher education, as set forth in section 23-3.1-104 (1)(p), C.R.S., any amounts owed for judicial fines, fees, costs, or surcharges, as set forth in section 16-11-101.8, C.R.S., any amounts owed for judicial restitution, as set forth in section 16-18.5-106.8, C.R.S., and other unpaid debts owing to the state or any agency thereof, as set forth in this subsection (3), then credit to the unpaid debts shall be prorated on the basis of the ratio of the amount of each such unpaid debt as compared to the total amount of unpaid debts.       Notwithstanding the provisions of subsection (1) of this section, in the case of the severance tax imposed by article 29 of this title, when an increase in the value of any product is subject to the approval or affected by the actions of any agency of the United States, or the state of Colorado, or any court, the increased value shall be subject to this tax. In the event that the increase in value is disapproved or reduced as the direct or indirect result of the actions of any agency of the United States, the state of Colorado, or any court, either in whole or in part, then the amount of tax which has been paid on the disapproved or reduced part of the value shall be considered excess tax. Within one year following the final determination of value, any person who has paid any such excess tax may apply for a refund, and the executive director, upon proper finding, shall have the authority and duty to refund the amount of excess tax paid. Any refund may, at the discretion of the executive director, be made in the form of a credit against future tax payments.      On and after October 1, 2002, any warrant representing a refund of income tax imposed by article 22 of this title 39 or a grant for property taxes, rent, or heat or fuel expenses assistance allowed by article 31 of this title 39 that is not presented for payment within six months from its date of issuance shall be void. On and after October 1, 2002, upon the cancellation of a warrant in accordance with the standard operating procedures of the department or the state controller, the department shall forward to the state treasurer the name of the taxpayer as it appears on the warrant, the taxpayer identification number, the taxpayer's last-known address, the amount of the canceled warrant, and an amount of money equal to the amount specified in the warrant so that the state treasurer may make the refund pursuant to the “Revised Uniform Unclaimed Property Act”, article 13 of title 38.    The department may reclaim from the unclaimed property fund and credit to the appropriate state revenue fund any amount forwarded by the department to the state treasurer pursuant to paragraph (a) of this subsection (5) that was based on a warrant representing an erroneous refund or grant. If the state treasurer issued an erroneous refund or grant to the person named on the warrant, the treasurer shall provide proof of that payment to the department and the department may assess that amount pursuant to section 39-21-103 (1).       Repealed.      On and after October 1, 2010, any warrant representing a refund issued by the department, excluding refunds addressed by subsection (5) of this section, that is not presented for payment within six months from its date of issuance shall be void. On and after October 1, 2010, upon the cancellation of a warrant in accordance with the standard operating procedures of the department or the state controller, the department shall forward to the state treasurer the name of the taxpayer as it appears on the warrant, the taxpayer identification number, the taxpayer's last-known address, the amount of the canceled warrant, and an amount of money equal to the amount specified in the warrant so that the state treasurer may make the refund pursuant to the “Revised Uniform Unclaimed Property Act”, article 13 of title 38.    The department may reclaim from the unclaimed property fund and credit to the appropriate state revenue fund any amount forwarded by the department to the state treasurer pursuant to paragraph (a) of this subsection (7) that was based on a warrant representing an erroneous refund or grant. If the state treasurer issued an erroneous refund or grant to the person named on the warrant, the treasurer shall provide proof of that payment to the department, and the department may assess that amount pursuant to section 39-21-103 (1).        History. Source: L. 65: P. 1137, § 2. C.R.S. 1963: § 138-9-7. L. 67: Pp. 847, 848, §§ 1, 2. L. 71: P. 1265, § 1. L. 77: (1)(a) amended and (4) added, pp. 1767, 1853, §§ 5, 7, effective January 1, 1978. L. 82: (3) amended, p. 558, § 1, effective April 6. L. 83: (3) amended, p. 794, § 5, effective June 3; (3) amended, p. 654, § 2, effective June 10; (3) amended, p. 438, § 2, effective June 15. L. 84: (3)(a) amended and (3)(b)(IV) added, pp. 1008, 1010, §§ 3, 4, effective March 29; (3) amended, p. 1011, § 1, effective April 27; (3)(b)(IV) repealed and (3)(b) amended, pp. 1125, 1126, §§ 47, 48, effective June 7. L. 85: (3)(a)(I), (3)(a)(VI), and (3)(b) amended, p. 1366, § 39, effective June 28; (3)(a)(I), (3)(a)(III), and (3)(b) amended, p. 602, § 22, effective July 1. L. 88: (3)(a)(I) amended, p. 637, § 19, effective July 1. L. 89: (3)(a)(I) and (3)(b) amended and (3)(a)(VII) added, p. 1195, § 4, effective June 7; (3)(a)(I) amended, p. 799, § 34, effective July 1; (1)(a) amended, p. 1595, § 8, effective July 1, 1993. L. 94: (3)(a)(I), (3)(a)(III), and (3)(a)(VII) amended, p. 3135, § 299, effective July 1. L. 96: (1)(a) amended, p. 164, § 4, effective July 1. L. 98: (3)(a)(II) amended, p. 91, § 5, effective March 23. L. 98, 2nd Ex. Sess.: (3)(a)(I) amended, p. 7, § 4, effective September 16. L. 99: (3)(a)(I) amended, p. 1317, § 5, effective August 4. L. 2001: (1)(a) and (3)(a)(I) amended, p. 778, § 11, effective June 1; (1)(a) amended, p. 233, § 2, effective August 8; (5) added, p. 619, § 4, effective August 8. L. 2002: (3)(a)(I) amended, p. 99, § 1, effective August 7. L. 2004: (1)(a) amended, p. 383, § 2, effective April 8; (3)(a)(I) amended, p. 576, § 35, effective July 1; (1)(b) repealed, p. 207, § 31, effective August 4; (3)(a)(I)(A) and (3)(b) amended and (3)(a)(VIII) added, p. 1259, § 4, effective August 4; (6) added, p. 315, § 3, effective August 4. L. 2009: (1)(a) and (3)(a)(I)(A) amended,(HB 09-1053), ch. 159, p. 690, § 14, effective August 5; (3)(a)(III), (3)(a)(IV), (3)(a)(V), and (3)(a)(VI) amended,(HB 09-1137), ch. 308, p. 1662, § 14, effective September 1. L. 2010: (6) repealed,(SB 10-212), ch. 412, p. 2032, § 1, effective July 1; (7) added,(SB 10-186), ch. 309, p. 1454, § 1, effective August 11. L. 2011: (1)(a) amended,(HB 11-1303), ch. 264, p. 1175, § 91, effective August 10. L. 2012: (3)(a)(I)(A) amended,(HB 12-1120), ch. 27, p. 112, § 31, effective June 1. L. 2013: (3)(a)(I)(A) amended,(SB 13-247), ch. 296, p. 1584, § 4, effective August 7. L. 2014: (3)(a)(I)(A) amended,(SB 14-019), ch. 10, p. 96, § 2, effective February 27. L. 2019: (5)(a) and (7)(a) amended,(SB 19-088), ch. 110, p. 470, § 18, effective July 1, 2020. L. 2021: (3)(a)(I)(A) and (3)(a)(V) amended,(SB 21-055), ch. 12, p. 78, § 15, effective March 21. History. Source: L. 65: P. 1137, § 2. C.R.S. 1963: § 138-9-7. L. 67: Pp. 847, 848, §§ 1, 2. L. 71: P. 1265, § 1. L. 77: (1)(a) amended and (4) added, pp. 1767, 1853, §§ 5, 7, effective January 1, 1978. L. 82: (3) amended, p. 558, § 1, effective April 6. L. 83: (3) amended, p. 794, § 5, effective June 3; (3) amended, p. 654, § 2, effective June 10; (3) amended, p. 438, § 2, effective June 15. L. 84: (3)(a) amended and (3)(b)(IV) added, pp. 1008, 1010, §§ 3, 4, effective March 29; (3) amended, p. 1011, § 1, effective April 27; (3)(b)(IV) repealed and (3)(b) amended, pp. 1125, 1126, §§ 47, 48, effective June 7. L. 85: (3)(a)(I), (3)(a)(VI), and (3)(b) amended, p. 1366, § 39, effective June 28; (3)(a)(I), (3)(a)(III), and (3)(b) amended, p. 602, § 22, effective July 1. L. 88: (3)(a)(I) amended, p. 637, § 19, effective July 1. L. 89: (3)(a)(I) and (3)(b) amended and (3)(a)(VII) added, p. 1195, § 4, effective June 7; (3)(a)(I) amended, p. 799, § 34, effective July 1; (1)(a) amended, p. 1595, § 8, effective July 1, 1993. L. 94: (3)(a)(I), (3)(a)(III), and (3)(a)(VII) amended, p. 3135, § 299, effective July 1. L. 96: (1)(a) amended, p. 164, § 4, effective July 1. L. 98: (3)(a)(II) amended, p. 91, § 5, effective March 23. L. 98, 2nd Ex. Sess.: (3)(a)(I) amended, p. 7, § 4, effective September 16. L. 99: (3)(a)(I) amended, p. 1317, § 5, effective August 4. L. 2001: (1)(a) and (3)(a)(I) amended, p. 778, § 11, effective June 1; (1)(a) amended, p. 233, § 2, effective August 8; (5) added, p. 619, § 4, effective August 8. L. 2002: (3)(a)(I) amended, p. 99, § 1, effective August 7. L. 2004: (1)(a) amended, p. 383, § 2, effective April 8; (3)(a)(I) amended, p. 576, § 35, effective July 1; (1)(b) repealed, p. 207, § 31, effective August 4; (3)(a)(I)(A) and (3)(b) amended and (3)(a)(VIII) added, p. 1259, § 4, effective August 4; (6) added, p. 315, § 3, effective August 4. L. 2009: (1)(a) and (3)(a)(I)(A) amended,(HB 09-1053), ch. 159, p. 690, § 14, effective August 5; (3)(a)(III), (3)(a)(IV), (3)(a)(V), and (3)(a)(VI) amended,(HB 09-1137), ch. 308, p. 1662, § 14, effective September 1. L. 2010: (6) repealed,(SB 10-212), ch. 412, p. 2032, § 1, effective July 1; (7) added,(SB 10-186), ch. 309, p. 1454, § 1, effective August 11. L. 2011: (1)(a) amended,(HB 11-1303), ch. 264, p. 1175, § 91, effective August 10. L. 2012: (3)(a)(I)(A) amended,(HB 12-1120), ch. 27, p. 112, § 31, effective June 1. L. 2013: (3)(a)(I)(A) amended,(SB 13-247), ch. 296, p. 1584, § 4, effective August 7. L. 2014: (3)(a)(I)(A) amended,(SB 14-019), ch. 10, p. 96, § 2, effective February 27. L. 2019: (5)(a) and (7)(a) amended,(SB 19-088), ch. 110, p. 470, § 18, effective July 1, 2020. L. 2021: (3)(a)(I)(A) and (3)(a)(V) amended,(SB 21-055), ch. 12, p. 78, § 15, effective March 21.    Editor's note:    Amendments to subsection (1)(a) by House Bill 77-1076 and Senate Bill 77-144 were harmonized.    Amendments to subsection (3) by Senate Bill 83-107 and Senate Bill 83-296 harmonized with House Bill 83-1445.    Amendments to subsection (3) by Senate Bill 84-171 and Senate Bill 84-32 were harmonized.    Amendments to subsection (3)(a)(I) and (3)(b) by Senate Bill 85-170 and House Bill 85-1380 were harmonized.    Amendments to subsection (3)(a)(I) by House Bill 89-1180 and Senate Bill 89-153 were harmonized.    Amendments to subsection (1)(a) by Senate Bill 01-125 and House Bill 01-1304 were harmonized.    Amendments to subsection (3)(a)(I)(A) by House Bill 04-1350 and Senate Bill 04-253 were harmonized.    The effective date for amendments to subsection (3)(a)(I)(A) by House Bill 12-1120 (chapter 27, Session Laws of Colorado 2012) was changed from August 8, 2012, to June 1, 2012, by House Bill 12S-1002 (First Extraordinary Session, chapter 2, p. 2432, Session Laws of Colorado 2012.)    Section 9 of chapter 10 (SB 14-019), Session Laws of Colorado 2014, provides that changes to this section by the act apply to income tax years commencing on or after January 1, 2013, and any other income tax years that are open under § 39-21-107 or 39-21-108.     Cross references:   For the legislative declaration contained in the 2001 act amending subsection (1)(a), see section 1 of chapter 95, Session Laws of Colorado 2001.   ANNOTATION   Law reviews. For article, “Taxation”, which discusses Tenth Circuit decisions dealing with interception of tax refunds for reimbursement of state child support, see 63 Den. U. L. Rev. 455 (1986).   Trial court erred in allowing state department of revenue to determine the form of the remedy for collecting an unconstitutional tax. It is the obligation of the trial court, after declaring the collected tax unconstitutional, to provide it with a remedy. Buckley Powder Co. v. State, 924 P.2d 1133 (Colo. App. 1996), aff'd in part and rev'd in part on other grounds, 945 P.2d 841 (Colo. 1997).   Issue of whether the state's offset of tax refunds against debts to the state was illegal did not involve statutory interpretation. Initially, it would have required resolution of the factual issue of whether the debts had been reduced to judgment pursuant to subsection (3)(a)(I). This factual determination is within the ambit of the administrator in the hearing. Kendal v. Cason, 791 P.2d 1227 (Colo. App. 1990).   Subsection (2) provides for a refund of all taxes overpayed by military retirees as a result of § 39-22-104 (4)(g) (now repealed) which was found to be unconstitutional. Kuhn v. State Dept. of Rev., 817 P.2d 101 (Colo. 1991).   Subsection (1)(a) effectively creates a four-year statute of repose. When read in combination with the applicable federal statute, the result is that no taxpayer may seek a refund of taxes in Colorado that were paid more than four years prior to the filing of a claim for a refund. Kuhn v. State Dept. of Rev., 897 P.2d 792 (Colo. 1995).   “Discovery rule” inapplicable. Unlike the usual type of statutory limitation period, which begins to run when the plaintiff knows or should have known of both the injury and its cause, subsection (1)(a) bars a claim after the specified period regardless of the date on which the claimant discovers the error or omission that gave rise to the claim. Kuhn v. State Dept. of Rev., 897 P.2d 792 (Colo. 1995).