“(1) The potential lost revenue in respect of an inaccuracy in a document …is the additional amount due or payable in respect of tax as a result of correcting the inaccuracy … (2) The reference in sub-paragraph (1) to the additional amount due or payable includes a reference to – (a) … (b) an amount which would have been repayable by HMRC had the inaccuracy … not been corrected. ”
“ (a) telling HMRC about it, (b) giving HMRC reasonable help in quantifying the inaccuracy…, and (c) allowing HMRC access to records for the purpose of ensuring that the inaccuracy … is fully corrected. ”
“ (1) P is liable under paragraph 1(1)(a) where a document which contains a careless inaccuracy (within the meaning of paragraph 3) is given to HMRC on P’s behalf. … (3) Despite sub-paragraphs (1) and (2), P is not liable to a penalty under paragraph 1 or 2 in respect of anything done or omitted by P’s agent where P satisfies HMRC that P took reasonable care to avoid inaccuracy (in relation to paragraph 1)… ”
“ The test to be applied, in my view, is to consider what a reasonable taxpayer, exercising reasonable diligence in the completion and submission of the return, would have done. ”
“ 21. What is reasonable care in any particular case will depend on all the circumstances. In my view this will include the nature of the matters being dealt with in the return, the identity and experience of the agent, the experience of the taxpayer and the nature of the professional relationship between the taxpayer and the agent. In my view, if a taxpayer reasonably relies on a reputable accountant for advice in relation to the content of his tax return then he will not be liable to a penalty under Schedule 24. ”