Penalties for Inaccuracies: Calculating the Penalty: Penalty reductions for quality of disclosure: Unprompted and prompted disclosure
You must check the date from which these rules apply for the tax or duty you are dealing with. See CH81011 for full details.
A disclosure is unprompted if it is made at a time when the person making it has no reason to believe that we have discovered or are about to discover the inaccuracy or under-assessment. Otherwise it is a prompted disclosure.
HMRC wants to encourage unprompted disclosures.
A disclosure will be treated as unprompted even if at the time it is made the full extent of the disclosure is not known, as long as the full details are provided within a reasonable time.
There can be no halfway house between an unprompted and prompted disclosure. It is either one or the other.
All the facts need to be considered before deciding if a disclosure is unprompted or prompted. You should apply a common sense approach in deciding whether or not a disclosure is unprompted and avoid making hasty judgements.
For guidance on how to determine if a disclosure is unprompted or prompted, see CH82421.