I suffered a loss on my CFD holdings of around £7000 for the tax year 2012-2013, which falls under the £10,000 Capital Gains Tax allowance.
Stock Trading vs Options Trading
(under the United Kingdom tax code). Can I claim back the tax (about £3000) or somehow offset the tax?
You are able to offset CGT losses against other capital gains.
As such if you for instance acquired a property making £50k of profit, you could offset the £7000 loss against this gain, resulting in a lower net capital gain of £42K. Unfortunately, you are not able to offset such losses against regular taxable income (say, as an employee) but you can always carry forward capital losses from the year into future years should you make a capital gain and offset it against gains made before tax.
Note also that if you report the loss on the self-assessment forms for the year, then you will be able to offset such a loss in future years (in the UK this is up to 6 years I believe) when you make more than the 10k CGT allowance.
Hence saving CGT in future years.