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HMRC internal manual

Claimant Compliance Manual

Opening and Working Enquiries: Reasons for enquiry not to be stated

You are not obliged to state your reasons for making the enquiry, and you should not do so in any case. You should not distinguish mandatory (random) enquiries from any other enquiries, as mandatory enquiries will be carried out in the same way and with an equal degree of thoroughness as risk - based enquiries.

You should therefore adopt a neutral approach when you open an enquiry.