Unfortunately capital gains tax is not as simple if you’ve made hundreds of transactions outside of your general account. - I do to and I have a google spreadsheet tracking everything up!
Note that this is general advice and I’m just doing some illustrations to show the complexities of apply the rules. You should get independent tax advice if you need to!
1. ISA is non-taxable
As you’ve said, your investments is in a general account (i.e. Non-ISA), because any profits / dividends is tax free within the ISA (Although if you do make a loss then you won’t get tax relief either).
2. No Sale = No Gain
Your account balance reflects the total value of your portfolio. So unfortunately the gain is not as simple as your closing balance less your opening balance, as you’ve said in one of the threads.
3. Report Threshold
As @rivorson said, you will have to report capital gains for the tax year if one of these are true:
a. Realised gains (profit) exceed the annual allowance £12,300 for 20/21.
b. The total sale proceeds (i.e. all the “Sell transactions” £ amounts added up) adds up to more than 4x the annual allowance.
c. You want to report any capital losses to be carried forward to future tax years.
4. How gains are calculated
Whenever you sell any shares:
i) you sell the shares that you acquired at the same day first.
ii) then you sell the shares you’ve acquired within 30 days on a first in first out basis,
iii) anything else is left in the general pool of shares you’ve acquired.
As an illustrative example, say someone made the following transactions within the tax year:
01-May, Purchased 600 shares at £10 each. (Total £6,000)
02-May, Purchased 400 shares at £11 each (Total £4,400)
15-May AM, Purchased 500 shares at £9 each (Total £4,500)
15-May PM, Sold 50 shares at £10 each (Total £500) - holding 1,450 shares
03-Jun, Sold 500 shares at £12 each (Total sale proceeds £6,000) - holding 1,000 shares
14-Jun, Sold 250 shares at £9 each (Total Sale proceeds £2,250) - holding 750 shares
15-Jun, Bought 1,250 shares at £11 each (Total £13,750) - holding 2,000 shares
July, Bought 2,000 shares at £15 each (Total £30,000) - Holding 4,000 shares
October - Sold all 4,000 shares at £14 each (Total sale proceeds £56,000) - Nil Shares left
Gain made on:
15-May, This lot is counted against the purchases we’ve made in the morning, so the gain is (£10 - £9) * 50 shares = £50. Note that if the sale was in the morning and purchase was at the evening, then the gain would be zero. (look back 30 days, 01-May & 02-May, First in First out, therefore look at 01-May first… (£10-£10) * 50 shares = 0)
No shares purchased on that day, so you go back 30 days and find the latest acquisition, which was on 15-May. There are 450 of the 15-May AM shares left, so you count against them first. No other shares purchased 30 days prior to the sale, so look at general pool for the remaining 50 shares…
First the 450 shares at a cost of £9 each = £4,050.
Then look for the remaining 50 shares from the general pool, (£6,000 + £4,400) / 1000 shares = £10.40 per share…
£10.40 * 50 shares = £520.
Total cost of shares = £4,570.
Sale Proceeds = £6,000.
Therefore Gain = £1,430.
Simply take the 250 shares from the general pool
Cost = £10.40 * 250 shares = £2,600
Sale Proceeds = £2,250
Loss of = (350)
Now we are just selling all of our shares, so the cost is:
750 shares in General pool (as calculated above) = 750 * £10.40 = £7,800
1,250 shares bought on 15-Jun = £13,750
2,000 shares bought in July = £30,000
Total Cost = £51,550
Sale Proceeds = £56,000
Gain of: £4,450
So therefore, just by looking at shares of company A, assuming the person have not made other asset disposals subject to capital gains tax, then
In the period, we’ve disposed shares with value of £64,250, which is over £49,200, so we will have to fill in a tax return.
The total gain is £5,530, which is below the £12,300 annual allowance limit, and therefore no CGT is payable.
Obviously things get more complicated if there’s stock splits etc!
Therefore depending on your circumstances, you might have to get some professional advice if you don’t know what you’re doing!
You can find out about the rules at: https://www.gov.uk/capital-gains-tax
Hope this helps