((a)) ** Suits by taxpayers for refund**

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

((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.

((c)) ** Suits by persons other than taxpayers**

((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)) ** 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.