Okla. Stat. tit. 68, § 2375 (2026)

Assessment or refund during IRS extension. A. On the original due date of the return, not including any extensions, the taxpayer shall remit therewith to the Tax Commission the amount of tax due under the applicable provisions of Section 2351 et seq. of this title. Failure to pay such tax on or before the date the return is due, not including any extensions, shall cause the tax to become delinquent. If the return is filed electronically, the amount of the tax due pursuant to the provisions of this article shall be due on or before the twentieth day of April following the close of the taxable year regardless of when the

return is electronically filed. The tax shall be deemed delinquent if unpaid after the twentieth day of April if the return is electronically filed. Provided, if the Internal Revenue Code provides for a later due date for returns of individuals, the Tax Commission shall accept payments made with returns filed by individuals by such date and such payments shall be considered as timely paid. B. If any tax due under Section 2351 et seq. of this title, except a deficiency determined under Section 221 of this title, is not paid on or before the date such tax becomes delinquent, a penalty of five percent (5%) of the total amount of the tax due shall be added thereto, collected and paid. However, the Tax Commission shall not collect the penalty assessed if the taxpayer remits the tax and interest within sixty (60) days of the mailing of a proposed assessment or voluntarily pays the tax upon the filing of an amended return. C. If any part of deficiency, arbitrary or jeopardy assessment made by the Tax Commission is based upon or occasioned by the refusal of any taxpayer to file with the Tax Commission any return as required by Section 2351 et seq. of this title, within ten (10) days after a written demand for such report or return has been served upon any taxpayer by the Tax Commission by registered letter with a return receipt attached, the Tax Commission may assess and collect, as a penalty, twenty-five percent (25%) of the amount of the assessment. In the exercise of the authority granted by subsection C of Section 223 and Section 224 of this title, the Tax Commission shall assess the tax as an estimated tax on the basis of its own determination of the Oklahoma taxable income of the taxpayer, to be adjusted if and when Oklahoma taxable income is ascertained under the provisions of Section 2351 et seq. of this title. D. If any part of any deficiency was due to negligence or intentional disregard, without the intent to defraud, then ten percent (10%) of the total amount of the deficiency, in addition to such deficiency, including interest as authorized by law, shall be added, collected and paid. E. If any part of any deficiency was due to fraud with intent to evade tax, then fifty percent (50%) of the total amount of the deficiency, in addition to such deficiency, including interest as herein provided, shall be added, collected and paid. F. The provisions in this section for penalties shall supersede all other provisions for penalties on income taxes. The provisions in this section for penalties shall supersede the provisions in the Uniform Tax Procedure Code, Section 201 et seq. of this title, only to the extent of conflict between such provisions and the penalty provisions in this section.

G. All taxes, penalties and interest levied under Section 2351 et seq. of this title must be paid to the Tax Commission at Oklahoma City, in the form or remittance required by and payable to it. H. 1. The period of time prescribed in Section 223 of this title, in which the procedures for the assessment of income tax may be commenced by the Tax Commission, shall be tolled and extended until the amount of taxable income for any year of a taxpayer under the Internal Revenue Code has been finally determined under applicable federal law and for the additional period of time hereinafter provided in this subsection. 2. If, in such final determination, the amount of taxable income for any year of a taxpayer under the Internal Revenue Code is changed or corrected from the amounts included in the federal return of the taxpayer for such year and such change or correction affects the Oklahoma taxable income of the taxpayer for such year, the taxpayer, within one (1) year after such final determination of the corrected taxable income, shall file an amended return under Section 2351 et seq. of this title reporting the corrected Oklahoma taxable income, and the Tax Commission shall make assessment or refund within two (2) years from the date the return required by this paragraph is filed and not thereafter, unless a waiver is agreed to and signed by the Tax Commission and the taxpayer. 3. In the event of failure by a taxpayer to comply with the provisions of paragraph 2 of this subsection, the statute of limitations shall be tolled for a period of time equal to the time between the date the amended return under this subsection is required until such return is actually furnished. 4. In administering the provisions of this subsection, the Tax Commission shall have the authority to audit each and every item of income, deduction, credit or any other matter related to the return where such items or matters relate to allocation or apportionment between the State of Oklahoma and some other state or the federal government even if such items or matters were not affected by revisions made in such final determination. Where such items or matters do not relate to allocation or apportionment between the State of Oklahoma and some other state or the federal government, the Tax Commission shall be bound by the revisions made in such final determination. 5. The provisions of this subsection shall be effective on September 1, 1993, and except in the case of tax years which are the subject of closing, settlement or resolution agreements entered into by taxpayers and the Tax Commission, keep open all tax years beginning after June 30, 1988, and all tax years beginning on or before June 30, 1988, for which extensions of the statute of limitations have been executed by the taxpayer, but only to the extent such extensions remain open on the date of enactment hereof.

Added by Laws 1971, c. 137, § 25, emerg. eff. May 11, 1971. Amended by Laws 1986, c. 218, § 23, emerg. eff. June 9, 1986; Laws 1989, c. 249, § 33, eff. Jan. 1, 1990; Laws 1992, c. 172, § 2, emerg. eff. May 5, 1992; Laws 1993, c. 273, § 7, emerg. eff. May 27, 1993; Laws 1994, c. 278, § 28, eff. Sept. 1, 1994; Laws 1997, c. 294, § 24, eff. July 1, 1997; Laws 1998, c. 385, § 10, eff. Nov. 1, 1998; Laws 2002, c. 458, § 13, emerg. eff. June 5, 2002; Laws 2007, c. 155, § 13, eff. Nov. 1, 2007; Laws 2014, c. 274, § 3, eff. Nov. 1, 2014; Laws 2023, c. 113, § 10, eff. July 1, 2023.