21(1)A person who fails to comply with section 47(3) of this Act is liable to a penalty equal to 5 per cent. of the relevant tax or, if it is greater or the circumstances are such that there is no relevant tax, to a penalty of £250; but this is subject to sub-paragraph (4) below.
(2)In sub-paragraph (1) above “relevant tax” means the tax (if any) for which the person concerned is liable for the period which—
(a)begins on the date with effect from which he is, in accordance with section 47 of this Act, required to be registered, and
(b)ends on the date on which the Commissioners received notification of, or otherwise became aware of, his liability to be registered.
(3)A person who fails to comply with section 47(4) of this Act is liable to a penalty of £250.
(4)Where, by reason of conduct falling within sub-paragraph (1) above—
(a)a person is convicted of an offence (whether under this Part of this Act or otherwise), or
(b)a person is assessed to a penalty under paragraph 18 above,
that conduct shall not also give rise to liability to a penalty under this paragraph.