This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Claimant Compliance Manual

Opening and Working Enquiries: Completion applications - customer(s) does not appeal against enquiry decision

If the customer(s) does not appeal against your enquiry decision, you will not be able to obtain any further information. You should conclude your enquiry in accordance with the guidance in CCM14000. You will only be able to consider the entitlement for the year further if you can make a discovery decision (see CCM13000). But you should, in appropriate cases, consider making a penalty determination (CCM10000).