SolvedIEIM8000650 | Reasonable Excuse
From HM Revenue & Customs · International Exchange of Information Manual
A penalty is not due if the RCASP or self-certification provider, satisfies an officer of HMRC, or following a successful appeal to the tribunal, that they had a reasonable excuse for the failure to comply, if the failure is remedied without unreasonable delay, once the excuse has ceased.
Reasonable excuse is a widely used concept in tax law, and additional guidance on its general application may be found at:
The following are not considered reasonable excuses:
An insufficiency of funds
That the person relies upon another person to do something