Every individual has a capital gains annual exemption. This is £10,100 (£20,200 for you and your wife) in the 2009/10 tax year.
If you own a property that is not your main residence, when this is sold you will pay capital gains tax on the proceeds less the cost. To benefit from two annual exemptions the property will need to be held in joint names.
If the property is in your name, you can transfer half to your wife and this will not generate a capital gain for you. The transfer can be made at any time right up to the point that you decide you are going to sell the property.
You only pay CGT if your overall gains are above the annual exemption for the tax year. The liability is not calculated for the period you own the asset.
For example, if you and your wife had purchased a property for £200,000 and sold it for £300,000 in 2009/10, the gain before applying the annual exemption would be £100,000. This would be split equally between you and your wife.
So, you would each have a gain in the 2009/10 tax year of £50,000 and would each pay CGT at 18 per cent on £39,900, the amount above the £10,100 annual exemption.