(1) Except as otherwise provided in this section: (a) A claim for refund must be filed within the period specified in s. 215.26(2); and (b) For purposes of this subsection, payments of estimated tax shall be deemed paid at the time such return is required to be filed under this code, determined with regard to any extensions of time allowed to the taxpayer under s. 213.055(2) or s. 220.222 for filing such return and not at such earlier time as such payments of estimated tax were actually made. This paragraph shall apply retroactively to tax years beginning on or after January 1, 2001. (2) For returns that were filed or taxes paid on or before September 30, 1994:
(a)1. A claim for refund shall be filed not later than 3 years after the date the return was filed or 1 year after the date the tax was paid, whichever is the later; and
2. No credit or refund shall be allowed or made with respect to the taxable year for which a claim was filed unless such claim is filed within such period.
(b) The amount of any credit or refund resulting from a claim for refund shall be limited as follows:
1. If the claim was filed during the 3-year period prescribed in this subsection, the amount of the credit or refund shall not exceed the portion of tax paid within the period, equal to 3 years plus the period of any extension of time for filing the return, immediately preceding the filing of the claim.
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 year immediately preceding the filing of the claim.
(c) For purposes of this subsection, a tax return filed on or before the last day prescribed by law for the filing of such return, determined without regard to any extensions thereof, shall be deemed to have been filed on such last day.