(1)In any case where, for a prescribed accounting period beginning after the day appointed under subsection (8) below,—
(a)a return is made which understates a person's liability to tax or overstates his entitlement to a payment under section 14(5) of the principal Act, or
(b)an assessment is made which understates a person's liability to tax and, at the end of the period of thirty days beginning on the date of the assessment, he has not taken all such steps as are reasonable to draw the understatement to the attention of the Commissioners,
and the circumstances are as set out in paragraph (a) or paragraph (b) of subsection (2) below, the person concerned shall be liable, subject to subsections (6) and (7) below, to a penalty equal to 30 per cent, of the tax which would have been lost if the inaccuracy had not been discovered.
(2)The circumstances referred to in subsection (1) above are as follows—
(a)that the tax for the period concerned which would have been lost if the inaccuracy had not been discovered—
(i)equals or exceeds 30 per cent, of the true amount of tax for that period, or
(ii)equals or exceeds whichever is the greater of £10,000 and 5 per cent, of the true amount of tax for that period ; or
(b)that the condition in subsection (3) below is fulfilled with respect to the period concerned and that, during any period of four years beginning not more than six years before the end of that period, there were at least two earlier prescribed accounting periods beginning after the day appointed under subsection (8) below in respect of each of which—
(i)either there was made such a return as is referred to in paragraph (a) of subsection (1) above or there was such an assessment as is referred to in paragraph (b) of that subsection and the person concerned did not, within the period there referred to, take all such steps as were reasonable to draw the understatement to the attention of the Commissioners; and
(ii)the condition in subsection (3) below was fulfilled.
(3)The condition referred to in subsection (2)(b) above is that the tax for the period concerned which would have been lost if the inaccuracy had not been discovered equals or exceeds 15 per cent, of the true amount of tax for that period.
(4)The references in subsections (1) to (3) above to the tax for a prescribed accounting period which would have been lost if an inaccuracy had not been discovered is a reference to the aggregate of—
(a)the amount (if any) by which credit for input tax for that period was overstated; and
(b)the amount (if any) by which output tax for that period was understated;
but if for any period there is an understatement of credit for input tax or an overstatement of output tax, allowance shall be made for that error in determining the tax for that period which would have been so lost.
(5)In subsections (2) (a) and (3) above " the true amount of tax ", in relation to a prescribed accounting period, means the amount of tax which was due from the person concerned for that period or, as the case may be, the amount of the payment (if any) to which he was entitled under section 14(5) of the principal Act for that period.
(6)Conduct falling within subsection (1) above shall not give rise to liability to a penalty under this section nor be taken into account under subsection (2) (b) above if—
(a)the person concerned satisfies the Commissioners or, on appeal, a value added tax tribunal that there is a reasonable excuse for the conduct, or
(b)at a time when he had no reason to believe that enquiries were being made by the Commissioners into his affairs, so far as they relate to tax, the person concerned furnished to the Commissioners full information with respect to the inaccuracy concerned.
(7)Where, by reason of conduct falling within subsection (1) above,—
(a)a person is convicted of an offence (whether under the principal Act or otherwise), or
(b)a person is assessed to a penalty under section 13 above,
that conduct shall not also give rise to liability to a penalty under this section and shall not be taken into account under subsection (2)(b) above.
(8)This section shall come into operation on such day as the Treasury may by order made by statutory instrument appoint.