148.076.  Claims for refund, filed when, how — amount, limitations. — 1.  A claim for credit or refund of an overpayment of any tax imposed by sections 148.010 to 148.110 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 by the taxpayer, within two years from the time the tax was paid.  No credit or refund shall be allowed or made after the expiration of the period of limitations prescribed in this subsection for the filing of a claim for credit or refund, unless a claim for credit or refund is filed by the taxpayer within such period.  Every claim for refund shall be filed with the director in writing and shall state the specific grounds upon which it is founded.  Claims for refund may be filed in accordance with section 143.851.

  2.  If the claim is filed by the taxpayer during the three-year period prescribed in subsection 1 of this section, 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 such 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.  If no claim is filed, the credit or refund shall not exceed the amount which would be allowable under either of the preceding sentences, as the case may be, if a claim was filed on the date the credit or refund is allowed.

  3.  If pursuant to subsection 4 of section 148.070 an agreement for an extension of the period for assessment of tax is made within the period prescribed in subsection 1 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 a 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 subsection 1 of this section if a claim had been filed on the date the agreement was executed.