710:50-5-13. Exceptions to statute of limitations 
(a)    When the Internal Revenue Service and the Taxpayer have consented in writing to an extension prior to the time allowed in 68 O.S. §223, the Tax Commission may assess or refund income tax, as imposed under Title 68, any time prior to the expiration of time agreed upon.
(b)    The Oklahoma Tax Commission may make assessment or refund after the expiration of time allowed in 68 O.S. §223 if corrections or changes are made by the Internal Revenue Service. The taxpayer shall notify the Oklahoma Tax Commission within one (1) year after such change or correction is made by the Internal Revenue Service and the Oklahoma Tax Commission shall, within two (2) years from the date of notification by the taxpayer, make such assessment or refund, unless a waiver between the taxpayer and the Oklahoma Tax Commission has been agreed to and signed. Failure to notify the Oklahoma Tax Commission of such changes shall cause the statute of limitations to be tolled.
(c)    The Commission shall have the authority to audit each and every item of taxable income, expense, credit or any other matter related to the return where such items are matters of allocation and/or apportionment between Oklahoma and some other state even if such items were not affected by revisions made by the Internal Revenue Service. Where items are not matters of allocation and/or apportionment between Oklahoma and some other state, the Commission shall be bound by the consequences of the assessment of income tax or refund of income tax made by the Internal Revenue Service after the amount of such net income has been finally ascertained.
(d)    Certain claims of military personnel, under conditions described in 68 O.S. §2358(D)(5) may not be barred by the 3-year limitation.
(e)    There is no statute of limitation for paying an established liability or for a liability on an unfiled return.
[Source: Amended at 10 Ok Reg 3837, eff 7-12-93; Amended at 11 Ok Reg 555, eff 11-10-93 (emergency); Amended at 11 Ok Reg 3497, eff 6-26-94]