I work in management accounts, so I could only answer this with a broad overview.
Someone recently asked me for my advice. Here is his situation:
Ran his own business as a sole trader for many years...didn't ever pay any VAT (and should have done) and didn't may much income tax. The HMRC caught up with him and sent him a huge bill which he initially paid on a quarterly basis, then stopped paying, sold his house and all other assets and lived on the cash for 2 years. He is now working as a sole trader again (different company name), putting everything through his partners bank, and not paying any income tax (doesn't turn over enough for VAT). He has basically 'disappeared' on paper and is hiding from HMRC.
He is now 8 years on from HMRC first finding out he owed them money. He thinks because it's over 6 years now that HMRC can no longer chase him for the initial money owed for VAT and income tax.
My advice to him was go see a qualified tax advisor, seek legal advice and start paying income tax now!!!
I'm just curious as to where he does go from here? I thought that there were no statute of limitation on tax owed, so there is no such thing as a '6 year rule? Am I right?