TFC71250 | Review of decision: information or evidence required to carry out a review
From HM Revenue & Customs · Tax-Free Childcare Technical Manual
Childcare Payments Act 2014, section 57(7)
If HMRC notify the person that they require further information or evidence to carry out a review, and that information or evidence is not supplied within 15 days of HMRC’s request to the person, the review will proceed without the evidence or information.