TFC60700 | Penalties: extension of time for requesting a review of appealing an assessment
From HM Revenue & Customs · Tax-Free Childcare Technical Manual
Childcare Payments Act 2014, section 45(8)
If a person has been granted an extension of the time limit for requesting a review of, or appealing against, an assessment under section 41 of the Act, any warning notice has no effect. This means that a further warning notice would need to be issued before they could be subject to a penalty.