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HMRC internal manual

Compliance Handbook

How to do a compliance check: types of compliance checks: joint working with other government agencies: advising another government agency

Exceptionally, HMRC officers may be asked to attend premises to advise another agency how to carry out their functions. Where the other agency is using criminal powers you may only attend if you are named on the warrant obtained by the other government agency. The warrant is the document issued by a legal or government official authorising the police or another body to make an arrest, search premises, or carry out some other action relating to the investigation of crime.

In any circumstances where you are advising another agency you must only act in an advisory capacity and must not participate in any search of the premises. You must not ask any questions of any person present although you may advise the other government agency on whose warrant you are named what questions they may ask in order to fulfil their functions. You must not carry out any HMRC functions.

There would be a clear conflict of powers if you carried out HMRC functions such as asking the person questions about their tax liability whilst you were named on a warrant obtained by another agency.  HMRC could lose a case at Tribunal where we have used civil powers but it appeared to the taxpayer that we were following criminal procedures.