§ 301.6511(a)-1(a) In the case of any tax (other than a tax payable by stamp):
§ 301.6511(a)-1(a)(1) If a return is filed, a claim for credit or refund of an overpayment must be filed by the taxpayer within 3 years from the time the return was filed or within 2 years from the time the tax was paid, whichever of such periods expires the later.
§ 301.6511(a)-1(a)(2) If no return is filed, the claim for credit or refund of an overpayment must be filed by the taxpayer within 2 years from the time the tax was paid.
§ 301.6511(a)-1(b) In the case of any tax payable by means of a stamp, a claim for credit or refund of an overpayment of such tax must be filed by the taxpayer within 3 years from the time the tax was paid. For provisions relating to redemption of unsued stamps, see section 6805.
§ 301.6511(a)-1(c) For limitations on allowance of credit or refund, special rules, and exceptions, see subsections (b) through (e) of section 6511. For limitations in the case of a petition to the Tax Court, see section 6512. For rules as to time return is deemed filed and tax considered paid, see section 6513.