OP, assuming you're a UK resident, you really don't want to be messing around with the likes of HMRC for instance. It may take them a while to uncover and investigate fraud - but they're a tenacious bunch, and when they do finally catch up with you, the ramifications can be pretty serious.
You appear to be unaware that any "ramifications" depend upon the amount of tax owed.
Replies
The greater the tax owed, the less tenacious HMRC will be to recover it and the less serious any "ramifications" will be. Although HMRC doesn't appreciate such deals becoming public knowledge:
https://www.theguardian.com/politics/2013/apr/29/hmrc-goldman-sachs-tax-osita-mba
So maybe there can be serious ramifications, just not for the party owing the tax.
The likes of Ebay also been leaned on to force payments into banks instead of PayPal now for similar reasons.
Credit cards have also been added to this type of stuff as well, not so strict, but there is tracking now.