I think they should set up a properly empowered intervention team in HM Revenue and Customs, with a remit to make all of 'em PAY IT BACK.
Thus anyone caught diddling expenses, house flipping, renting out to each other and claiming, setting up massive tax singularities - whether they got off any criminality charges or not - full recovery of every penny, however long it takes.
This should be staffed, by the way, by underpaid lower-ranking civil servants in HMRC who have dreamed for years of a payrise, or finally, doing a job they can be proud of. I suspect a few are weary of driving trivial diddlers in failing businesses to suicide for a few hundred quid of undeclared savings interest.