28 U.S.C. § 2401 : US Code - Section 2401: Time for commencing action against United States

      (a) Except as provided by chapter 71 of title 41, every civil
    action commenced against the United States shall be barred unless
    the complaint is filed within six years after the right of action
    first accrues. The action of any person under legal disability or
    beyond the seas at the time the claim accrues may be commenced
    within three years after the disability ceases.
      (b) A tort claim against the United States shall be forever
    barred unless it is presented in writing to the appropriate Federal
    agency within two years after such claim accrues or unless action
    is begun within six months after the date of mailing, by certified
    or registered mail, of notice of final denial of the claim by the
    agency to which it was presented.