INTM860260 | Diplomatic Missions: Communicating with privileged persons
From HM Revenue & Customs · International Manual
In any communication with a person entitled to diplomatic privilege do not use any expression that could be taken as a threat, such as possible distraint action or other legal proceedings.
Where tax is payable, tell debt management;
not to send a reminder if the tax is not paid following the initial request for payment, and
to report the facts to the Embassy Unit (see INTM860290) or customer unit responsible if the tax remains unpaid.
On receipt of a report from debt management, pass the case to an HO grade or above to make a personal written request for payment. If this has no result, report the case to BAI, Business International (Immunities & Privileges).