Tax avoidance measures could yield the public purse an extra £1bn, the Chancellor said.

These include an agreement with tax havens the Isle of Man and the Channel Islands.

The Chancellor fired a warning to those who try to avoid paying the tax they owe, saying “this government will not let you get away with aggressive tax avoidance”.

Today also finalises long-awaited anti-tax avoidance legislation due to take effect in April.

Nearly three years after the first draft of a General Anti Abuse Rule (GAAR) was drawn up – and heavily promoted in last year’s budget – the clampdown will come into force in the Finance Bill 2013.

The measure will counteract tax advantages arising from abusive tax avoidance arrangements. The GAAR will apply to income tax, corporation tax (including amounts treated as corporation tax), capital gains tax, inheritance tax, petroleum revenue tax and stamp duty land tax.

It will also apply to the annual residential property tax due to be enacted with effect from 1 April 2013.

Separate legislation will be introduced later to apply the GAAR to National Insurance contributions (NICs).

A tax on foreign-owned mansions could bring in a further £0.2bn, Capital Economics said.

Earlier, Osborne said the Office for Budget Responsibility had sharply revised down its future growth forecast for the eurozone. For the UK, it estimated growth for 2013 would be 0.6%, then 1.8% next year, 2.3% in 2015, 2.7% in 2016 and 2.8% in 2017.