Tax investigators are being handed an extra £77 million to target global companies and wealthy individuals who dodge paying their fair share.
Chancellor George Osborne insisted the package showed the Government was determined to "go after" aggressive avoiders and evaders, branding the behaviour "unacceptable".
The move follows widespread condemnation of big-name firms like Starbucks, Google and Amazon for paying little or no corporation tax in the UK. A string of celebrities have also been accused of using aggressive tax avoidance schemes.
The funding package, which covers the next two years, was confirmed ahead of this week's mini-budget, which is expected to deliver bleak news for benefit claimants as well as the wealthy. Economists expect Mr Osborne to make an humiliating climbdown over one of the coalition's key goals - to have debt falling as a share of national income by 2015/16.
The boost for HM Revenue and Customs is part of a scheme to raise tax take by £10 billion. The cash injection will help speed up work challenging multinationals' transfer pricing arrangements to stop global companies using legal loopholes to shift profits out of the UK.
A hundred new investigators will be recruited, and a "centre of excellence" established within HMRC to focus expertise on tackling offshore evasion and avoidance.
HMRC's wider operations will be supported with another £70 million of funding in 2013-14 and 2014-15, details of which will be announced in the Autumn statement.
Mr Osborne said: "The Government is clear that while most taxpayers are doing their bit to help us balance the books, it is unacceptable for a minority to avoid paying their fair share, sometimes by breaking the law. We are determined to tackle this problem and HMRC are making good progress, but we are giving them additional tools to bring in more.
It is very important that people who try to avoid their taxes understand that we are going after them. In Britain we want successful businesses, we want a very competitive tax system. But people have to pay those taxes that are due, and that includes multinational companies."
The Government is also proposing a crackdown on "cowboy" tax advisers who sell aggressive tax avoidance schemes, with tougher disclosure rules and penalties. And the chancellor is poised to confirm a deal with Switzerland that will raise more than £5 billion in previously uncollected taxes from Swiss bank accounts over the next six years.