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

HMRC internal manual

Claimant Compliance Manual

End of year: Interaction with S19 Enquiries

If you have closed your examination (whether or not on the basis that you have obtained all the information you needed for your purposes), you will still be able to enquire into the claimant’s entitlement to tax credits, and the amount of their award, for the year under S19. The action you have already taken as part of your examination will not prejudice your right to enquire into the award. But the S18(10) notice might impact on the amount of time you have to open an enquiry.

You will only have one opportunity to make formal enquiry into the award after the end of year. So your enquiry will have to cover not only any risks you consider you were not able to address fully as part of your examination, but also any that subsequently come to light and are worthy of enquiry. For this reason, it will not be appropriate to convert an examination into an enquiry.

You should never close an in-year examination and immediately open an enquiry to continue, in effect, with the examination.