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HMRC internal manual

Complaint Handling Guidance

Dealing with complaints: Complaints arising from interest disputes in direct taxes

So far as direct taxes are concerned, only the Interest Review Unit (IRU) can agree to set aside the payment of a properly made interest charge. The IRU become involved in two types of complaint cases: where the customer is unhappy with the IRU’s decision on an interest objection; and where the tier 1 or tier 2 complaint is wholly or partly about interest. Please refer to the IRU’s guidance on dealing with complaints of this kind.