xmlns:atom="http://www.w3.org/2005/Atom"
23. For the purposes of this Part—
(a)a person shall be deemed not to have failed to do anything required to be done within a limited time if it was done within such further time, if any, as HMRC may have allowed; and
(b)where a person had a reasonable excuse for not doing anything required to be done—
(i)that person shall be deemed not to have failed to do it unless the excuse ceased; and
(ii)after the excuse ceased, that person shall be deemed not to have failed to do it if it was done without unreasonable delay after the excuse had ceased.