Are you a tax abuser?

The Treasury has announced that it will include Inheritance Tax in the taxes targeted by a new rule to clamp down on tax dodgers.

Inheritance Tax -- which raises £2.7bn a year -- will joint Income Tax, National Insurance, Corporation Tax, Stamp Duty and other levies in the scope of a new General Anti-Abuse Rule which will be brought into being next year.

So what will be an abuse? And will any attempt to reduce your tax bill be classed as aggressive and against the rules?

It's clear that taxpayers who have recognised tax-free investments, such as ISAs and pensions, won't be affected.

It seems that those who set up companies to receive their income and pay less tax will be in the clear as well.

What about people who don't pay income tax on the savings interest because they have offset mortgages?

Or employees who give up some of their salaries in exchange for pension contributions or childcare vouchers (so-called "salary sacrifice") - and hence pay less National Insurance?

At this stage the assumption has to be that most or all of these things will be fine, because the government is aiming its fire at well-off investors and businesses which use artificial tax-avoiding schemes.

The Treasury says the rule will be narrow and won't affect what it calls "the centre ground of tax planning".

But this is still a grey area and no one's quite sure yet what the definition of "tax abuse" is going to be.