Sch 2 para 7
(1) If, on a claim made to the Board, it appears to their satisfaction that a company has been assessed to the same amount of windfall tax more than once, the Board shall direct that so much of any assessment made on that company under this Schedule as appears to them to be excessive is to be vacated. (2) A claim under sub-paragraph (1) above— (a) must be made in such form as the Board may require; and (b) shall not be made after the end of the period of six years beginning with the day of the service on the claimant of the notice of the most recent assessment to which the claim relates. (3) On the giving of a direction under this paragraph with respect to any assessment, that assessment shall be vacated to the extent specified in the direction.