‘the service is deemed to be effected by properly addressing, pre-paying and posting a letter containing the document, and, unless the contrary is proved, to have been effected at the time at which the letter would be delivered in the ordinary course of post.’
“[71]…In our view, knowledge in this context refers to the serving party’s actual knowledge or what might be called his constructive knowledge, ie knowledge which he could have acquired exercising reasonable diligence” 77. ..... 78. HMRC did not agree that the reference to last known place of residence would have the same meaning in the TMA as the similar phrase in the CPR: in other words, HMRC did not accept that HMRC were required to exercise some due diligence for the purposes of s 115(2) TMA. However Mr Jones did not really suggest any reason why the two phrases would have different meanings. 79. Nevertheless, I do accept that a different level of due diligence may be required for s 115(2) than for the CPR. A claimant and defendant might have no relationship and certainly the defendant may have no responsibility to keep the claimant informed of his current address. On the other hand, HMRC do require taxpayers to complete tax returns, a part of which requires the taxpayer to inform HMRC of their address. So a taxpayer does have some sort of responsibility or duty to keep HMRC appraised of their address and therefore the obligation on HMRC to make enquiries about the taxpayer’s address are, I think, less than they would be on a claimant using the CPR. 80. But in principle I think the dicta in Marshall v Maggs apply and HMRC have some responsibility for ascertaining the taxpayer’s address. When the Court of Appeal said that some due diligence would be required of the claimant, they were referring to “knowledge which he could have acquired exercising reasonable diligence”