How many years can HMRC go back?

This is one of the most common FAQs I get, so it’s posted in the FAQ section, and it’s also below:

If HMRC have found significant errors – these could be for relatively small amounts of money – they can open up earlier years for examination. It starts at four years, then if they can prove your errors are careless they can go back six years and if they can prove the errors are deliberate they can go back twenty years. If you’ve been running a business and you have failed to tell HMRC about the business it’s called a ‘failure to notify chargeability’ – and that means they can go back twenty years.

Other FAQs here.

If you have a Q that’s not covered in the FAQ do let me know.