5. Work out if you need to pay

You need to pay Capital Gains Tax when you sell an asset if your total taxable gains are above your annual Capital Gains Tax allowance.

Work out your total taxable gains

  1. Work out the gain for each asset (or your share of an asset if it’s jointly owned). Do this for the personal possessions, shares, property or business assets you’ve disposed of in the tax year.

  2. Add together the gains from each asset.

  3. Deduct any allowable losses.

The tax year runs from 6 April to 5 April the following year.

You’ll need to report and pay Capital Gains Tax if your taxable gains are above your allowance.

If your total gains are less than the tax-free allowance

You don’t have to pay tax if your total taxable gains are under your Capital Gains Tax allowance.

There are different rules for reporting a loss.

Even if your gains are below the tax-free allowance, tell HM Revenue and Customs (HMRC) if:

  • you disposed of chargeable assets with an overall worth of more than 4 times the Capital Gains Tax allowance - this works out as £45,200 for the 2017 to 2018 tax year but was less for previous years
  • you have losses that you want to claim

Report this in your tax return. If you’re not registered for Self Assessment, you can write to HMRC instead.

If you don’t have anything to report

If you’re not registered for Self Assessment you don’t need to do anything.

If you’re registered for Self Assessment you must still fill in the capital gains section of your tax return. To do this:

  1. Confirm that you need to complete the capital gains section in ‘Tailor your return’.

  2. In the ‘Details of chargeable assets…’ page select ‘No’ for each question - you won’t need to report anything else about your capital gains or losses.

Send your tax return by the usual deadlines for Self Assessment.

If you’re non-resident

You need to tell HMRC when you sell residential property even if your gain is below the tax-free allowance or you make a loss. Non-residents don’t pay tax on other capital gains.