Delaware Code
Subchapter III. Procedure and Administration
§ 539. Limitations on credit or refund.

(a) Claim for credit or refund of an overpayment of any tax imposed by this title or Title 4 shall be filed by the taxpayer within 3 years from the last date prescribed for filing the return (or in the case of license fees or taxes under Part III of this title, 3 years from the expiration date of the license to which such overpayment relates) or within 2 years from the time the tax was paid, whichever of such periods expires the later, or if no return was filed by the taxpayer, within 2 years from the time the tax was paid. No credit or refund shall be allowed or made after the expiration of the period of limitation prescribed in the preceding sentence for the filing of a claim for credit or refund, unless a claim for credit or refund is filed with the Director by the taxpayer within such period.
(b) (1) If the claim for credit or refund was filed by the taxpayer during the 3-year period prescribed in subsection (a) of this section, the amount of the credit or refund shall not exceed the portion of the tax paid within the period immediately preceding the filing of the claim, equal to 3 years plus the period of any extension of time for filing the return.
(2) If the claim was not filed within such 3-year period, the amount of the credit or refund shall not exceed the portion of the tax paid during the 2 years immediately preceding the filing of the claim.
(3) If no claim was filed, the credit or refund shall not exceed the amount which would be allowable under either paragraph (b)(1) or (2) of this section, as the case may be, if claim was filed on the date the credit or refund is allowed.
(c) If an agreement under the provisions of § 531(f) of this title extending the period for assessment of a tax imposed by this title or Title 4 is made within the period prescribed in subsection (a) of this section for the filing of a claim for credit or refund:

(1) The period for filing claim for credit or refund or for making credit or refund if no claim is filed, provided in subsection (a) of this section, shall not expire prior to 6 months after the expiration of the period within which an assessment may be made pursuant to the agreement or any extension thereof under § 531(f) of this title; and
(2) If a claim is filed, or a credit or refund is allowed when no claim was filed, after the execution of the agreement and within 6 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 the 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 subsection (b) of this section if a claim had been filed on the date the agreement was executed.
(d) If the taxpayer is required by § 514 of this title to report a change or correction in federal income or estate liability reported on the federal tax return for any taxable period, or to file an amended tax return under this title with the Director, a claim for credit or refund of any resulting overpayment of tax under this title shall be filed by the taxpayer within 2 years from the time such report or amended return was required to be filed with the Director. If such a report or amended return required by § 514 of this title is not filed within the 90-day period specified in that section, interest on any resulting credit or refund shall not accrue for the period after such ninetieth day and prior to the forty-fifth day after the date of filing the claim for credit or refund. The amount of any such credit or refund shall not exceed the amount of the reduction in tax attributable to such federal change or correction or attributable to the items amended on the taxpayer's amended federal tax return. This subsection shall not affect the time within which a claim for credit or refund may be filed, or the amount for which a credit or refund may be made, without regard to this subsection.
(e) If the claim for credit or refund relates to an overpayment attributable to a net operating loss carry back or a capital loss carry back, in lieu of the 3-year period of limitation prescribed in subsection (a) of this section, the period shall be that period which ends 3 years after the time prescribed by law for filing the return (including extensions thereof) for the taxable year of the net operating loss or net capital loss which results in such carry back, or the period prescribed in subsection (c) of this section in respect of such taxable year, whichever expires later. In the case of such a claim, the amount of the credit or refund may exceed the portion of the tax paid within the period provided in subsection (b) or (c) of this section, whichever is applicable, to the extent of the amount of the overpayment attributable to such carry back.
(f) For purposes of this section, tax shall be deemed to have been paid on the date determined in accordance with § 540(c) of this title.
(g) In the case of an individual:

(1) The running of the periods specified in this section with respect to individuals shall be suspended during any period of such individual's life that such individual is financially disabled.
(2) For purposes of paragraph (g)(1) of this section, an individual is financially disabled if such individual is unable to manage that individual's own financial affairs by reason of a medically determinable physical or mental disability (excluding disability caused by voluntary use of alcohol or unlawful use of a controlled substance defined in Chapter 47 of Title 16) 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 12 months.
(3) An individual shall not be treated as financially disabled during any period that such individual's spouse, guardian or any other person is authorized to act on behalf of such individual in financial matters.