HM Revenue & Customs (HMRC) is to crackdown on people abusing the self-assessment system to claim back money they're not entitled to.
Up to 400 people will be targeted in London and the south east by a special taskforce which is expected to recover £6 million for the Treasury.
Those caught will face a hefty fine and possibly criminal prosecution.
Special HMRC taskforces have been created to target people who 'are not playing by the rules'.
HMRC has launched 35 taskforces since last year with the first putting the spotlight on the restaurant trade.
The taskforces are expected to reclaim £90 million from this year's tax cheat targets.
HMRC's Jennie Granger, director general enforcement and compliance, said: "The message is clear - if you choose to defraud the tax system or seek to evade tax, we can and will track you down."
Other crackdowns launched
As well as targetting fradulent southerners HMRC has announced three other groups it will be looking at from today.
There will be taskforces focussing on tax-dodging in Northern Ireland, the jewellery trade in the Midlands and fast food outlets in East Anglia .
In it together
The crackdown should help flush out those not willing to play fair.
Last year high profile figures such as Jimmy Carr and Gary Barlow were exposed as using a variety of schemes to limit their tax bill.
While big companies like Google, Amazon and Starbucks were investigated for not paying their dues like everyone else.
Self-assessment can be difficult to get your head around, so don't risk the taxman knocking down your door.
If you want to make sure you're filling out everything correctly read this useful article: How to get your online self-assessment tax return right.