Every individual is entitled to realise a capital gain, such as on the sale of shares or property, and up to £11,100 of this for the current tax year is tax free. If you do not use this allowance, you will lose it. Therefore if you have assets which are currently carrying a gain, then you could consider selling these assets to make use of the allowance.
You could then buy back these shares (after 30 days have passed) and assuming that the share price has not increased significantly, you will have uplifted the base cost of the shares tax free. If you feel that the share price may increase significantly over the 30 day period, your spouse could arrange to buy the shares off the market at the same time that you sell the shares to the market, thus keeping the shares in the family.
Careful planning is required but you could reduce any future capital gains tax bill by up to £3,000.Share