Capital Gains Tax on PAYE

I currently work full time and am on PAYE and ofcourse I earn more than the income tax personal allowance threshold and so pay income tax, but this is all dealt with through HR / automatically on PAYE at the company I work for.

In addition to my job, I trade stocks on the side and am consistently making good profits every week. Most of my stock purchases are in the US so I avoid paying Stamp Duty. I do sometimes buy stocks on the LSE when I see a good deal come by. I know that during this tax year I don’t expect to be earning more than the capital gains tax threshold (around £12,000). So my question is:

  1. Do I need to fill out some self assessment or declare my earnings, even though it is less than the capital gains tax threshold.
  2. If I go above the capital gains tax threshold, do I need an accountant to help me to do the paper work or is it easy enough to do myself?
  3. Is the route for declaring your capital gains tax the same if you are also working full time on PAYE as opposed to being self-employed?
  1. If it’s less than the CGT annual allowance, then you don’t need to pay CGT or report it to HMRC (unless you’re already registered for SA and your total disposals exceed 4 times the annual exemption, in which case - you do).

  2. No, it’s a simple enough self-assessment that you can do yourself, although you’re free to get an accountant if you wish.

  3. Yes, you fill out a self-assessment form.


@ 777GE90

Great question - saves me asking it :slight_smile:

Thanks, very helpful.

It can be a bit tricky to calculate the CGT - particularly if shares in the same company were bought on multiple occasions before selling. Worth remembering to offset the share dealing / stamp duty costs as well.

Is there like a template on how they expect you to give the breakdown?

You’d fill an online version of this ( in, with accompanying notes and guidance (


Very helpful, thanks.

See “Do I pay tax on my investments?” section of this post: How much tax will I pay? - Money tips blog