26 U.S.C. § 6532. Periods of limitation on suits

1. (a)
   (a)

   Suits by taxpayers for refund

   1. (1)
      (a)(1)

      General rule

      No suit or proceeding under section 7422(a) for the recovery of any internal revenue tax, penalty, or other sum, shall be begun before the expiration of 6 months from the date of filing the claim required under such section unless the Secretary renders a decision thereon within that time, nor after the expiration of 2 years from the date of mailing by certified mail or registered mail by the Secretary to the taxpayer of a notice of the disallowance of the part of the claim to which the suit or proceeding relates.
   2. (2)
      (a)(2)

      Extension of time

      The 2-year period prescribed in paragraph (1) shall be extended for such period as may be agreed upon in writing between the taxpayer and the Secretary.
   3. (3)
      (a)(3)

      Waiver of notice of disallowance

      If any person files a written waiver of the requirement that he be mailed a notice of disallowance, the 2-year period prescribed in paragraph (1) shall begin on the date such waiver is filed.
   4. (4)
      (a)(4)

      Reconsideration after mailing of notice

      Any consideration, reconsideration, or action by the Secretary with respect to such claim following the mailing of a notice by certified mail or registered mail of disallowance shall not operate to extend the period within which suit may be begun.
   5. (5)
      (a)(5)

      Cross reference

      For substitution of 120-day period for the 6-month period contained in paragraph (1) in a title 11 case, see section 505(a)(2) of title 11 of the United States Code.
2. (b)
   (b)

   Suits by United States for recovery of erroneous refunds

   Recovery of an erroneous refund by suit under section 7405 shall be allowed only if such suit is begun within 2 years after the making of such refund, except that such suit may be brought at any time within 5 years from the making of the refund if it appears that any part of the refund was induced by fraud or misrepresentation of a material fact.
3. (c)
   (c)

   Suits by persons other than taxpayers

   1. (1)
      (c)(1)

      General rule

      Except as provided by paragraph (2), no suit or proceeding under section 7426 shall be begun after the expiration of 2 years from the date of the levy or agreement giving rise to such action.
   2. (2)
      (c)(2)

      Period when claim is filed

      If a request is made for the return of property described in section 6343(b), the 2-year period prescribed in paragraph (1) shall be extended for a period of 12 months from the date of filing of such request or for a period of 6 months from the date of mailing by registered or certified mail by the Secretary to the person making such request of a notice of disallowance of the part of the request to which the action relates, whichever is shorter.