4(1)An assessment under paragraph 2 or 3 above of an amount of aggregates levy due for any accounting period—
(a)shall not be made more than two years after the end of the accounting period unless it is made within the period mentioned in sub-paragraph (2) below; and
(b)subject to sub-paragraph (3) below, shall not in any event be made more than three years after the end of that accounting period.
(2)The period referred to in sub-paragraph (1)(a) above is the period of one year after evidence of facts sufficient in the Commissioners' opinion to justify the making of the assessment first came to their knowledge.
(3)Subject to sub-paragraph (4) below, where aggregates levy has been lost—
(a)as a result of any conduct for which a person has been convicted of an offence involving fraud,
(b)in circumstances giving rise to liability to a penalty under paragraph 1 of Schedule 4 to this Act (failure to notify of registrability etc.), or
(c)as a result of conduct falling within paragraph 7(1) of Schedule 6 to this Act (evasion),
that levy may be assessed under paragraph 2 or 3 above as if, in sub-paragraph (1)(b) above, for “three years” there were substituted “twenty years”.
(4)Where, after a person’s death, the Commissioners propose to assess an amount of aggregates levy as due by reason of some conduct of the deceased—
(a)the assessment shall not be made more than three years after the death; and
(b)if the circumstances are as set out in sub-paragraph (3) above—
(i)the modification of sub-paragraph (1) above contained in that sub-paragraph shall not apply; but
(ii)any assessment which (applying that modification) could have been made immediately after the death may be made at any time within three years after it.
(5)Nothing in this paragraph shall prejudice the powers of the Commissioners under paragraph 2(4) above.