A broker statement can tell you what happened inside one account, but it cannot tell you where the complete investment position belongs on your UK tax return.
A sale of listed shares may feed SA108, while dividends and cash interest belong on SA100 and foreign income may require SA106. Activity inside an ISA or pension is normally excluded altogether. The calculation also has to work across brokers, because HMRC’s matching rules do not restart each time you use a different platform.
Finbooks brings those accounts into one UK tax calculation, separates gains from income and prepares the figures for the relevant Self Assessment sections. This guide explains how to move from your broker history to a return ready for the 31 January 2027 deadline.
What you need to know for 2025/26
The 2025/26 tax year ran from 6 April 2025 to 5 April 2026; the online return and outstanding tax are normally due by 31 January 2027.
Eligible activity inside an ISA or registered pension is normally kept outside your personal capital gains and investment-income reporting.
Listed share and ETF disposals usually go on SA108, while dividends and interest are reported separately through SA100 or SA106.
The Capital Gains Tax Annual Exempt Amount is £3,000 and the Dividend Allowance is £500 for 2025/26.
A complete calculation must combine the same holding across taxable brokers, convert foreign transactions into pounds and preserve earlier acquisition costs.
Which investments and income go on your Self Assessment?
Begin with the account rather than the asset name. A share held inside a Stocks & Shares ISA is normally outside Self Assessment, while the same share held in a General Investment Account can create reportable dividends and a capital gain or loss when sold.
| Investment activity | Typical UK tax treatment | Usual reporting route |
|---|---|---|
| Investments held inside an ISA or registered pension | Eligible gains and income remain within the tax wrapper; losses cannot normally be claimed outside it. | Not normally reported on your personal SA100 or SA108. |
| Sell listed shares, investment trusts or qualifying listed ETFs | A capital gain or allowable loss, calculated in pounds under HMRC’s matching rules. | SA108, Listed shares and securities. |
| Sell unlisted or AIM shares | A capital gain or allowable loss, with separate treatment for any relief or election claimed. | SA108, Unlisted shares and securities. |
| Receive UK company dividends | Dividend income, including amounts covered by the Dividend Allowance. | SA100, UK dividends. |
| Receive fund distributions | Dividend or interest income depending on the fund and distribution type, including automatically reinvested amounts. | SA100 or SA106, according to the fund. |
| Receive cash interest or bond coupons | Savings income rather than a capital gain. | SA100 for UK interest; SA106 may be needed for foreign interest. |
| Receive foreign dividends | Foreign income reported in pounds, with overseas withholding tax considered separately. | SA100 for limited amounts where its conditions apply; otherwise SA106. |
| Dispose of an interest in a non-reporting offshore fund | The gain is normally an offshore income gain charged to Income Tax rather than Capital Gains Tax. | SA106, Other overseas income and gains. |
| Close an option, future, CFD or other derivative | Capital treatment is common for private investors, but the contract and nature of the activity can change the result. | SA108 or the relevant income pages, depending on the facts. |
Your broker’s profit is not your UK taxable gain
The platform may use its own cost basis, account currency and trade matching. HMRC requires sterling values and applies the same-day rule, the following 30-day rule and the Section 104 pool across every taxable account in which you hold the same shares in the same capacity.
When do you need the Capital Gains Tax pages?
HMRC’s 2025/26 SA108 notes require the capital gains pages in several situations, including where chargeable gains before losses exceeded the £3,000 Annual Exempt Amount, assets disposed of were worth more than £50,000, or you want to claim an allowable loss. Other gains, claims and elections can also make SA108 necessary.
The £50,000 test looks at disposal proceeds rather than profit. Selling £55,000 of shares at a loss can therefore produce a reporting requirement for someone already completing Self Assessment, even though no Capital Gains Tax is due.
If this is the first year in which you need Self Assessment, you would normally tell HMRC by 5 October 2026. Paper returns are normally due by 31 October 2026, while an online return and the tax owed are due by 31 January 2027.
How are dividends and interest reported?
Enter the full dividend and interest amounts required by the return; HMRC applies the relevant allowances when calculating the tax. For 2025/26, the Dividend Allowance is £500, while the Personal Savings Allowance is normally £1,000 for a basic-rate taxpayer, £500 for a higher-rate taxpayer and nil for an additional-rate taxpayer.
UK company dividends belong in the dividend section of SA100. Distributions from authorised unit trusts, OEICs and investment trusts can use a different SA100 field, while foreign dividends and interest may require SA106. Reinvestment does not remove the income: accumulation units and dividend reinvestment plans can create taxable amounts without sending cash to your bank account.
SA100 only provides limited shortcuts for foreign income
The 2025/26 SA100 includes fields for untaxed foreign interest up to £2,000 and foreign dividends up to £500, subject to the form’s conditions. Use SA106 where the amounts or relief claimed fall outside those limits, and report foreign tax separately rather than subtracting it without explanation.
Why do offshore ETFs and funds need an extra check?
UK reporting-fund status changes both the income reported while you hold an offshore fund and the treatment when you sell it. A reporting fund can create excess reportable income even when no cash distribution appears in your broker account; that income is normally reported through SA106 and can increase the allowable cost used when the fund is sold.
A disposal of shares or units in a reporting fund is generally within Capital Gains Tax. A gain on a non-reporting offshore fund is normally an offshore income gain instead and belongs on SA106. Check the exact fund and share class against HMRC’s reporting funds list, because the broker’s label or ticker does not establish the UK status.
2025/26 is the first year of the Foreign Income and Gains regime
Qualifying new residents may claim relief on eligible foreign income and gains during their first four years of UK residence after at least ten consecutive years of non-UK residence. A claim uses SA109 alongside the relevant SA106 or SA108 entries and can affect access to the Personal Allowance and CGT Annual Exempt Amount, so it should not be treated as an automatic exemption.
How do you report investments on your 2025/26 Self Assessment?
The figures entered on the return should be the result of a calculation, not a copy of each broker’s annual profit. Start by creating one history across your taxable accounts, then route each total to the section that matches its tax treatment.
Prepare the figures in Finbooks
- 1
Import the complete broker history: iInclude every taxable account used during 2025/26 and earlier acquisitions still held or sold during the year.
- 2
Separate wrappers from taxable accounts: keep ISA and pension activity outside the taxable calculation while preserving transfers into or out of those wrappers for review.
- 3
Reconcile transfers and corporate actions: check stock splits, mergers, spin-offs, rights issues, fees and movements between your own accounts before calculating gains.
- 4
Convert each relevant amount into pounds: foreign purchases, sales, dividends and withholding tax need sterling values at the appropriate dates; converting only the final dollar or euro profit is not enough.
- 5
Apply UK matching across brokers: Finbooks combines same-day acquisitions, purchases during the following 30 days and the remaining Section 104 pool for each holding.
- 6
Generate the 2025/26 Self Assessment figures: review capital disposals, dividends, interest, foreign income and losses before transferring the final totals.
Activate the sections you need in HMRC Online
Use Tailor your return to activate the Capital Gains Tax and Foreign sections where required. SA100 already contains the principal UK interest and dividend fields, while SA106 and SA108 appear when the relevant supplementary sections are selected.
A portfolio spread across UK and overseas platforms may use all three forms. That does not mean the same amount should be entered three times: each total belongs in the section matching its source and tax treatment.
Map the investment figures to SA100, SA106 and SA108
| Return section | What usually goes there | What to check |
|---|---|---|
| SA100 boxes 1 and 2 | Taxed and untaxed UK interest. | Use the interest credited for the year, not the closing cash balance. |
| SA100 box 4 | Dividends from UK companies. | Enter the full dividend amount required by the form, including amounts within the allowance. |
| SA100 box 5 | Other dividends, including relevant authorised unit trust, OEIC and investment-trust distributions. | Include reinvested distributions where applicable. |
| SA100 boxes 3, 6 and 7 | Limited foreign interest and dividend amounts where the SA100 conditions apply. | Check the £2,000 interest and £500 dividend limits and whether foreign tax relief is being claimed. |
| SA106 | Foreign interest, dividends, withholding tax, excess reportable income and offshore income gains. | Report the correct sterling amounts and consider Foreign Tax Credit Relief separately. |
| SA108 boxes 23 to 30 | Listed shares and securities, including the number of disposals, proceeds, allowable costs, gains and losses. | Use totals calculated under HMRC’s matching rules across all taxable brokers. |
| SA108 boxes 31 to 38 | Unlisted shares and securities. | Review any relief, negligible-value claim or election separately. |
| SA108 boxes 14 to 22 | Other property, assets and gains that do not belong in a more specific section. | Use this route only after identifying the instrument and contract correctly. |
| SA109 | Residence information and claims under the 2025/26 FIG regime. | A FIG claim also needs corresponding entries on SA106 or SA108. |
For listed shares, the paper SA108 asks for the number of disposals, disposal proceeds, allowable costs, gains before losses and losses in boxes 23 to 27. Boxes 28 to 30 deal with claims or elections and amounts already reported through HMRC’s Real Time Transaction service. HMRC Online may use descriptive labels instead of displaying every paper box number.
What happened to the 2024/25 Box 51 adjustment?
The one-off split around 30 October 2024 applied when the main CGT rates changed during 2024/25. Box 51 remains available for genuine CGT adjustments, but an ordinary 2025/26 share or ETF calculation does not need to separate gains around that date because the 18% and 24% rates apply throughout the tax year.
What should you check before submitting your investment return?
Read the finished return against the complete portfolio rather than checking each platform separately. A figure can agree perfectly with one broker statement and still be wrong because a matching purchase, foreign dividend or fund distribution sits elsewhere.
Your final 2025/26 investment filing check
ISA and pension activity has been separated from taxable accounts.
Every taxable broker and earlier acquisition feeding a Section 104 pool is included.
Transfers between accounts you beneficially own have not been treated as sales.
Purchases, disposals, income and foreign tax have been converted into pounds at the appropriate dates.
UK dividends, foreign dividends, interest and capital disposals have not been netted into one platform-profit figure.
Accumulation-fund income and excess reportable income have been considered even where no cash was received.
Allowable current-year and brought-forward capital losses have been included correctly.
The SA100, SA106 and SA108 totals agree with the final Finbooks reports and supporting transactions.
Once those checks agree, submit the return and keep the HMRC receipt with the Finbooks reports and original broker files. That preserves the route from each figure in Self Assessment back to the transaction, exchange rate and tax treatment behind it.
Bring investments and crypto into the same tax position
Finbooks keeps taxable brokerage activity, investment income and crypto within one UK tax record, while preserving the different rules and reporting routes that apply to each category.
If crypto also forms part of your portfolio, continue with our guide to reporting crypto on your 2025/26 UK Self Assessment. The two calculations meet in the same return and share the same allowances, tax bands and pool of available capital losses.
Investment Self Assessment questions
You may still need SA108 if your total disposal proceeds exceeded £50,000, you want to claim a capital loss or another reporting condition applies. The £3,000 Annual Exempt Amount concerns net chargeable gains rather than the total value sold.
Gains and losses on listed shares and qualifying listed ETFs usually go in the Listed shares and securities section of SA108, boxes 23 to 30 on the 2025/26 paper form. Unlisted and AIM shares use the separate Unlisted shares and securities section.
UK company dividends generally go in box 4 of SA100, with certain fund distributions in box 5. Limited foreign dividends can use SA100 where its conditions apply; otherwise report them through SA106 with any foreign tax shown separately.
Eligible gains and income arising inside an ISA are not normally included in your personal SA100 or SA108. Losses inside the ISA cannot normally be claimed against taxable gains outside the wrapper.
No. HMRC’s share-matching rules apply to the same shares held in the same capacity across all your taxable accounts, so a sale with one broker can depend on a purchase made through another.