Oddly enough, the Inland Revenue itself offers a range of tricks to make the CGT bill disappear. Some of them involve accepting a bit of risk.
If you are willing to invest in an unquoted trading company, there is considerable scope for sheltering any gain. Firstly, reinvestment relief, which requires you to buy shares, or subscribe for new ones, in a qualifying company.
The key to "qualifying" is that it is a UK business, it trades (rather than invests in property, for example), doesn't do certain prohibited trades (including giving tax advice!) and it is not quoted on the main Stock Exchange. A share listed on the Alternative Investment Market will qualify.
You have quite a long time scale to do the investment - one year before to three years after your disposal that gave rise to the gain. And you only have to invest your gain - not the whole of the proceeds. You may not wish to reinvest direct - or may not find it easy to identify the right company. Fortunately, companies are increasingly getting Revenue approval under a new clearance scheme. A good investment adviser should have a few for you to consider.
Or you may wish to spread your risk. Venture capital trusts (VCTs) are springing up which offer opportunities for some income tax relief at 20 per cent on your investment. They also offer the chance to shelter the capital gain.
There is a pounds 100,000 limit on how much you can invest in a year. Going a stage further, if you really have found the company you want to put your money into, and are willing to subscribe for new shares, the enterprise investment scheme allows you to get reliefs in the same way as a VCT.
All of these reliefs are geared to getting the taxpayer to put money into a riskier environment, channelling funds to companies that traditionally find it hard to attract finance.
Bear in mind that the gain that you have deferred will pop out when you sell the new investment - but the same opportunity for deferral may be there again, though whether the reliefs last under a change of government is an interesting question.
There is also an automatic and full relief that must not be forgotten. Retirement relief gives full relief for gains of up to pounds 250,000 and half- relief on the balance of gains up to pounds 1m. What do you have to do? Sell that business!
Most trading businesses qualify and - provided you have been fully involved for 10 years - you can expect very substantial relief. There are a lot of quirks, though, oddly, two key ones favour the taxpayer. First, you don't actually have to retire - you can keep working. Second, 50 is the normal qualifying threshold.
Overall, you can play fiscal magic and make your gain disappear, perhaps only for a while - but a gain deferred is no bad thing.
The catch is you have to do it carefully - there is always a risk you end up with a broken egg rather than a rabbit when you reach into the top hat to retrieve your investment.
John Whiting is a tax partner with Price Waterhouse.