IEIM905400 - Reasonable Excuse
No penalty will be due if a person has a reasonable excuse for a failure to comply with any of the requirements of the regulations, if the failure was rectified without unreasonable delay once the reasonable excuse had ceased.
Reasonable excuse is a widely used concept in tax law, and additional guidance on its general application may be found at:
https://www.gov.uk/tax-appeals/reasonable-excuses
In the context of these regulations in particular, a lack of funds will not be a reasonable excuse, nor will relying on another person to do something.