Capital gains tax (CGT) is charged on profits when certain assets are sold. Everyone has an annual CGT exemption, which currently is £11,300 in the 2017-18 tax year. This means that any gains you have achieved up to that amount is not subject to tax.
The £11,300 is a 'use it or lose it' type of allowance, meaning you cannot carry it forward to future years. But remember that each individual has their own allowance, so a married couple can potentially realise gains of £22,600 this tax year without incurring any tax. It is possible also transferring assets between spouses and civil partners tax-free, so it might make sense to consider transferring your holdings to a spouse in a lower tax bracket or one who hasn't used their allowance as yet.
Typically in trading it is worth offsetting any losses against your gains. Profits and losses realised in the same tax year have to be offset against each other, and this will reduce the amount of your gain subject to tax. If your losses exceed your profits, you can carry them forward to offset against profits in the future, provided you have registered those losses with HMRC.
The end of the financial year is soon approaching, do not lose out on your annual exemption.
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