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HMRC internal manual

Compliance Handbook

How to do a compliance check: penalty for an inaccuracy in response to notices: disclosed inaccuracy

When we require a person to produce a document they have no choice but to give us the document. They must not alter the document to correct any inaccuracy. If they know that the document contains an inaccuracy then they must tell us about it when they produce the document to us, even if we may already know. If they do this, we will not charge a penalty.

If the person later discovers an inaccuracy and takes reasonable steps to tell us about it, then the inaccuracy may still be penalised if it was made carelessly in the first place. However, you should give credit for the disclosure in setting the amount of the penalty, if any.

An inaccuracy that was not careless or deliberate will not be penalised if the person takes reasonable steps to tell us about the inaccuracy when they find out about it.