(a) General. Claim for credit or refund of an overpayment of income tax shall be filed by the taxpayer within three years from the time the return was filed or two years from the time the tax was paid, whichever of such periods expires the later, or if no return was filed, within two years from the time the tax was paid. If the claim is filed within the three year period, the amount of the credit or refund shall not exceed the portion of the tax paid within the three years immediately preceding the filing of the claim plus the period of any extension of time for filing the return. If the claim is not filed within the three year period, but is filed within the two year period, the amount of the credit or refund shall not exceed the portion of the tax paid during the two years immediately preceding the filing of the claim. Except as otherwise provided in this section, if no claim is filed, the amount of a credit or refund shall not exceed the amount which would be allowable if a claim had been filed on the date the credit or refund is allowed.
(b) Extension of time by agreement. If an agreement under the provisions of paragraph two of subdivision (c) of section 11-1783 (extending the period for assessment of income tax) is made within the period prescribed in subdivision (a) of this section for the filing of a claim for credit or refund, the period for filing a claim for credit or refund, or for making credit or refund if no claim is filed, shall not expire prior to six months after the expiration of the period within which an assessment may be made pursuant to the agreement or any extension thereof. The amount of such credit or refund shall not exceed the portion of the tax paid after the execution of the agreement and before the filing of the claim or the making of the credit or refund, as the case may be, plus the portion of the tax paid within the period which would be applicable under subdivision (a) of this section if a claim had been filed on the date the agreement was executed.
(c) Notice of federal change or correction. A claim for credit or refund of any overpayment of tax attributable to a federal change or correction required to be reported pursuant to section 11-1759 shall be filed by the taxpayer within two years from the time the notice of such change or correction or such amended return was required to be filed with the commissioner of taxation and finance. If the report or amended return required by section 11-1759 is not filed within the ninety day period therein specified, no interest shall be payable on any claim for credit or refund of the overpayment attributable to the federal change or correction. The amount of such credit or refund shall not exceed the amount of the reduction in tax attributable to such federal change, correction or items amended on the taxpayer's amended federal income tax return. This subdivision shall not affect the time within which or the amount for which a claim for credit or refund may be filed apart from this subdivision.
(d) Overpayment attributable to net operating loss carryback. A claim for credit or refund of so much of an overpayment as is attributable to the application to the taxpayer of a net operating loss carryback shall be filed within three years from the time the return was due (including extensions thereof) for the taxable year of the loss, or within the period prescribed in subdivision (b) of this section in respect of such taxable year, or within the period prescribed in subdivision (c) of this section, where applicable, in respect of the taxable year to which the net operating loss is carried back, whichever expires the latest.
(e) Failure to file claim within prescribed period. No credit or refund shall be allowed or made, except as provided in subdivision (f) of this section or subdivision (d) of section 11-1790, after the expiration of the applicable period of limitation specified in this chapter, unless a claim for credit or refund is filed by the taxpayer within such period. Any later credit shall be void and any later refund erroneous. No period of limitations specified in any other law shall apply to the recovery by a taxpayer of moneys paid in respect of taxes under this chapter.
(f) Effect of petition to tax commission. If a notice of deficiency for a taxable year has been mailed to the taxpayer under section 11-1781 and if the taxpayer files a timely petition with the tax commission under section 11-1789, it may determine that the taxpayer has made an overpayment for such year (whether or not it also determines a deficiency for such a year). No separate claim for credit or refund for such year shall be filed, and no credit or refund for such year shall be allowed or made, except:
(1) as to overpayments determined by a decision of the tax commission which has become final; and
(2) as to any amount collected in excess of an amount computed in accordance with the decision of the tax commission which has become final; and
(3) as to any amount collected after the period of limitation upon the making of levy for collection has expired; and
(4) as to any amount claimed as a result of a change or correction described in subdivision (c) of this section.
(g) Limit on amount of credit or refund. The amount of overpayment determined under subdivision (f) of this section shall, when the decision of the tax commission has become final, be credited or refunded in accordance with subdivision (a) of section 11-1786 and shall not exceed the amount of tax which the tax commission determines as part of its decision was paid:
(1) after the mailing of the notice of deficiency, or
(2) within the period which would be applicable under subdivision (a), (b) or (c) of this section, if on the date of the mailing of the notice of deficiency a claim had been filed (whether or not filed) stating the grounds upon which the tax commission finds that there is an overpayment.
(h) Early return. For purposes of this section, any return filed before the last day prescribed for the filing thereof shall be considered as filed on such last day, determined without regard to any extension of time granted the taxpayer.
(i) Prepaid income tax. For purposes of this section, any tax paid by the taxpayer before the last day prescribed for its payment, any income tax withheld from the taxpayer during any calendar year, and any amount paid by the taxpayer as estimated income tax for a taxable year shall be deemed to have been paid by him or her on the fifteenth day of the fourth month following the close of his or her taxable year with respect to which such amount constitutes a credit or payment.
(j) Return and payment of withholding tax. Notwithstanding subdivision (h) of this section, for purposes of this section with respect to any withholding tax:
(1) if a return for any period ending with or within a calendar year is filed before April fifteenth of the succeeding calendar year, such return shall be considered filed on April fifteenth of such succeeding calendar year; and
(2) if a tax with respect to remuneration paid during any period ending with or within a calendar year is paid before April fifteenth of the succeeding calendar year, such tax shall be considered paid on April fifteenth of such succeeding calendar year.
(k) Running of periods of limitation suspended while taxpayer is unable to manage financial affairs due to disability.
(1) In the case of an individual taxpayer, the running of the periods specified in subdivisions (a), (b), and (c) of this section shall be suspended during any period of such individual's life that such individual is financially disabled. For purposes of this subdivision, an individual taxpayer is an individual who is subject to the tax imposed under this chapter.
(2) For purposes of paragraph one of this subdivision, an individual taxpayer is financially disabled if such individual is unable to manage his or her financial affairs by reason of a medically determinable physical or mental impairment of that individual which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than twelve months. An individual shall not be considered to have such impairment unless proof of the existence thereof is furnished in such form and manner as the commissioner of taxation and finance may require.
(3) An individual taxpayer shall not be treated as financially disabled during any period that such individual's spouse or any other person is authorized to act on behalf of such individual in financial matters.
(l) Cross-reference. For provision barring refund of overpayment credited against tax of a succeeding year, except for good cause shown, see subdivision (e) of section 11-1786.