ECP5700 | How to apply the penalties: Record of decision making
From HM Revenue & Customs · Excise Civil Penalties Manual
When issuing a penalty you must record the factors you have taken into account, including the effect on compliance.
You will also need to retain some or all of the following records depending on the circumstances of the case
visit reports
working papers
control / audit notes
letters to and from the taxpayer
a note of relevant questions you have asked the taxpayer and their replies
details of record produced including records such as annual accounts and stock accounts
details of notices issued to the taxpayer
schedules.