COP9 can be either issued or asked for in relation to tax on any aspect of your business or personal affairs. However, it can only be used for ‘deliberate’ problems, where a tax fraud has been committed.
HMRC also has other disclosure routes available, including the worldwide disclosure facility (WDF) and the digital disclosure service (DDS). If you have errors that are not particularly serious, perhaps an innocent error, it may be that one of these routes is more appropriate. We would be happy to discuss your issue and then let you know what route is most appropriate.
If you have a tax issue where you have committed a fraud, COP9 may be the best option since it provides protection from a criminal investigation.