Tories make stealth tax pledge

But the rule would not have applied to the most controversial recent policies, such as the scrapping of the 10p income tax rate and plans to raise car tax on gas-guzzlers.

A convention that proposals with "technical content" should first be set out in the previous pre-Budget report (PBR) is one recommendation of a review by former Chancellor Geoffrey Howe.

It would have included Alastair Darling's proposals to change capital gains tax and to levy a charge on so-called "non-doms" but not simple rate changes.

Lord Howe's report, due to be formally unveiled, also proposes a tax simplification watchdog to examine the system and recommend changes to a new joint committee of MPs and peers.

Mr Osborne said: "Ten years of Gordon Brown's stealth taxes have destroyed people's trust in the system and given us the most complicated tax regime in the world.

"The Conservative government is going to overhaul the way tax laws are made so that they are simpler and more transparent.

"With these changes suggested by the former Chancellor of the Exchequer, Geoffrey Howe, there will be no more stealth taxes.

"Future governments will no longer be able to bury the bad news in the small print. It's another example of the Conservatives setting the agenda on the economy."

The Bill putting Mr Darling's first Budget into law was finally passed by the Commons on Wednesday night - but only after Labour MPs were talked out of a revolt by promises of a re-examination of tax hikes.