Six numbers go on SA108, and getting them right means matching every disposal against same-day buys, the next thirty days, then the Section 104 pool. The UK pack does that matching across all your accounts and fills boxes 23 to 27 and box 45.
Each line of the Self Assessment capital gains pages, and how far the pack takes it before you sign.
| Item | The rule | Form and box | What the pack produces |
|---|---|---|---|
| Share and fund disposals | Gains above the £3,000 annual exempt amount are charged at 18% for basic-rate taxpayers and 24% for higher and additional rate. | SA108 boxes 23 to 27 | Prepared Number of disposals, proceeds, allowable costs, gains and losses, with the allowance taken off and the rate split shown underneath. |
| Matching and pooling | A disposal matches same-day acquisitions first, then anything bought in the next thirty days, and only then the Section 104 pool at averaged cost. | Behind boxes 24 to 26 | Prepared Every disposal names the rule that matched it, and each holding keeps a visible pool ledger. |
| Losses brought forward | Losses carried in from earlier years come off only what is left above the annual exempt amount, so the allowance is never spent on them. | SA108 box 45 | Prepared You choose which carried-forward pots to apply, and the sheet takes them off the gains still standing above the allowance. |
| Offshore fund income | A reporting fund can allocate income it never paid out. It is taxable as income and it raises the cost of the units that earned it. | SA106 | Prepared Gross excess reportable income per fund, the equalisation reduction, the taxable amount and the deemed distribution date, with interest and dividend subtotals. |
| Dividends | Dividends are income, not gains. The first £500 is free, then 10.75%, 35.75% or 39.35% for 2026/27. | SA100 main return | Partly The dividend report totals income per holding. You apply the allowance and your dividend rate. |
| ISA and SIPP holdings | Gains and dividends inside a Stocks and Shares ISA or a SIPP carry no CGT and no dividend tax, and never reach Self Assessment. | Not reported | Tracked, not taxed Tag the account as ISA or Pension in the accounts step and it stays in your portfolio but out of the return. |
| Submitting the return | SA108 is filed alongside the SA100 Self Assessment return. | SA108 with SA100 | You file Everything leaves as a file for you or your accountant. |
Enter your trades in one stock or fund to see how each sale is matched and estimate the tax for the year. No account needed.
Boxes 23 to 27 and box 45 sit at the top with the HMRC revision the sheet was built against. Below them the annual exempt amount comes off and the taxable gain is split between the basic and higher rate bands. Open a holding and you see which rule matched each disposal, and open its ledger and you see the pool cost move with every buy and sell.
Open the UK pack
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Thirty-day matching and pooling only run across the accounts you put in the return, so the pack asks before it calculates. Each card carries the wrappers a British investor really holds: taxable, ISA, or a pension such as a SIPP, plus whose account it is. Turn an account off and its trades leave the return and the matching together, which is why an ISA or a pension is worth marking properly.
See the accounts stepAllInvestView
The finished pack leaves as PDF, Excel or CSV with the disposal detail and the pool ledgers attached. While a figure is still blocked the buttons stay inactive, because a partial SA108 is worse than none. Close the year and the calculation revision freezes, so the file you send and the file you keep agree.
See what exportsAllInvestView
It does not file with HMRC. The rate split uses the taxable income you enter, so treat the tax figure as an estimate and not as your assessed liability.
The UK calculation covers listed shares and securities and the reporting-fund income that attaches to them. It is built against the SA108 revision for the tax year you open, and where an instrument cannot be verified as listed, or an exchange rate or a reporting-fund figure is missing, it blocks that total instead of filling it in.
For 2026/27, 6 April 2026 to 5 April 2027, the Capital Gains Tax annual exempt amount is £3,000 per individual, the same as 2025/26 and down sharply from £12,300 a few years ago. Gains above it on shares and funds are taxed at 18% for basic-rate taxpayers and 24% for higher and additional-rate taxpayers. Those rates have applied since 30 October 2024 and were left alone at the Autumn 2025 Budget. Your rate depends on where the gain sits once stacked on your income, so a single disposal can be part-taxed at 18% and part at 24%.
The UK does not use simple FIFO for shares. All shares of the same class in the same company form a Section 104 holding, a single pool with an averaged cost that is apportioned pro rata when you sell part of it. Before the pool, HMRC applies matching rules in order:
A fund with UK reporting status can allocate income to you that it never actually paid. It is taxable as income on the deemed distribution date, six months after the fund's reporting period ends, and it also increases the cost of the units that earned it, so the same money is not taxed again as a gain later.
Fund houses publish these figures in reports that rarely reach investors. Record what your fund reported, together with any equalisation on units you bought mid-period, and the pack carries the taxable amount to SA106 and the cost uplift into the Section 104 pool at the same time.
Dividends are taxed under income tax rather than CGT. The first £500 is tax-free, unchanged for 2026/27. Above it:
| Band | 2025/26 | 2026/27 |
|---|---|---|
| Basic rate | 8.75% | 10.75% |
| Higher rate | 33.75% | 35.75% |
| Additional rate | 39.35% | 39.35% |
The basic and higher dividend rates rose by 2 percentage points from 6 April 2026, announced at the Autumn 2025 Budget. The additional rate is unchanged. Notes still showing 8.75% and 33.75% are on the 2025/26 figures.
Gains and dividends inside a Stocks and Shares ISA, annual allowance £20,000, or a SIPP are free of CGT and dividend tax and are not reported on Self Assessment. Only a taxable general investment account reaches SA108. Hold the wrappers in AllInvestView for the complete picture and mark them in the accounts step so they never inflate a reportable gain.
Not tax advice. This page summarises the main UK investment tax rules for the 2025/26 and 2026/27 tax years. Rates and rules change and your circumstances differ. Confirm your position with HMRC or a qualified tax adviser before acting.
One import, and the pooling, the thirty-day matching and the reporting-fund income stay right for the whole tax year.
The Capital Gains Tax annual exempt amount is 3,000 pounds for individuals in both the 2025/26 and 2026/27 tax years, and 1,500 pounds for most trusts. Gains above this are taxed at 18% for basic-rate taxpayers and 24% for higher and additional-rate taxpayers.
For 2026/27 the dividend tax rates are 10.75% basic, 35.75% higher and 39.35% additional, after a 500 pound tax-free dividend allowance. The basic and higher rates rose by 2 percentage points from the 2025/26 rates of 8.75% and 33.75%, effective 6 April 2026.
Section 104 pooling groups all shares of the same class in the same company into a single pool with an averaged cost. When you sell part of the holding, the cost is apportioned pro rata from the pool. It replaces per-lot FIFO for most UK share disposals.
UK matching rules apply before the Section 104 pool: disposals are matched first to shares bought on the same day, then to shares bought in the next 30 days, the bed and breakfast anti-avoidance rule, and only then to the pool. This stops you crystallising a loss and immediately rebuying the same share to keep it.
No. Gains and dividends inside a Stocks and Shares ISA or a SIPP are free of CGT and dividend tax and are not reported on your Self Assessment. Only holdings in a taxable general investment account go on the SA108 capital gains pages.
Boxes 23 to 27 for the listed shares and securities section: number of disposals, disposal proceeds, allowable costs, gains before losses and losses in the year, plus box 45 for losses brought forward and used. It also shows the annual exempt amount and the taxable gain below those boxes.
The pack prepares a separate SA106 sheet for reporting offshore funds you held: gross excess reportable income per fund, the equalisation reduction, the taxable amount, the deemed distribution date, and interest and dividend subtotals. That income also raises the pooled cost it belongs to, so the gain is not taxed twice.