The real time Capital Gains Tax service lets a UK resident report gains on assets other than UK residential property online, without waiting for a Self Assessment return. For a gain in the 2025 to 2026 tax year you must report by 31 December 2026 and pay by 31 January 2027, so reporting early does not bring the payment date forward; it gives you a payment reference and certainty sooner.
What is the real time Capital Gains Tax service?
GOV.UK offers two routes for reporting gains on shares and investments, cryptoassets, business assets, personal possessions and other assets that are not UK residential property: a Self Assessment return for the tax year, or the real time service. The real time service is an online form you complete after signing in to HMRC online services. It currently accepts gains on assets sold in the 2025 to 2026 and 2026 to 2027 tax years.
It should not be confused with the separate 60 day return for UK residential property, which is compulsory and has its own Capital Gains Tax on UK property account.
Who can use it, and what can it not be used for?
According to GOV.UK, you must be UK resident to use the service, and you cannot use it to report for someone else, such as a client, a trust or an estate. That means agents cannot file it for clients. You also cannot use it to report:
- gains on UK residential property;
- foreign tax credit relief for overseas property;
- chargeable event gains on life insurance policies.
Non residents report all disposals of UK property, residential or not; GOV.UK says they do not report or pay tax on other gains.
Do you need to report at all?
You need to report and pay if your total taxable gains for the year, after allowable losses, exceed the annual exempt amount, which is £3,000 for 2026 to 2027. If you are already in Self Assessment, GOV.UK says you must also report gains in your return where your total disposal proceeds were more than £50,000, for 2023 to 2024 onwards, even if no tax is due.
Losses do not have to be reported straight away; GOV.UK allows up to 4 years after the end of the tax year of the disposal. The calculation itself follows the normal rules in how capital gains tax is calculated.
When must you report and pay?
| Tax year of the gain | Report by | Pay by |
|---|---|---|
| 2025 to 2026 | 31 December 2026 | 31 January 2027 |
| 2026 to 2027 | 31 December 2027 | 31 January 2028 |
After you report, HMRC sends a letter or email with a 14 character payment reference starting with X. You use it to pay through HMRC’s online payment service, by card, by bank transfer to the HMRC Shipley account or by cheque. GOV.UK warns that using the wrong reference can delay a payment or send it to a different tax bill. A fee applies for corporate credit or debit cards. To correct a report, you submit a new one quoting the report reference starting with RTT that is emailed to you after first use.
Does reporting early change when the tax is due?
No. The payment date is 31 January after the end of the tax year whichever route you use, matching the balancing payment date for Self Assessment in section 59B of the Taxes Management Act 1970. Reporting in, say, June 2026 for a gain made in May 2026 gives you a figure and a reference to pay early if you want, but the legal deadline does not move.
The service also does not create payments on account. Section 59A TMA 1970 bases payments on account on income tax, and GOV.UK says the 31 January balancing payment includes anything owed for capital gains. A large one off gain therefore does not inflate next year’s payments on account, whichever route you use to report it.
How does it fit with Self Assessment?
GOV.UK is clear on one point: if you are already registered for Self Assessment, you must also include the details of the sale in your Self Assessment return. The real time report does not replace the return for people who file one.
The service is most useful for someone who is not otherwise in Self Assessment, for example an employee taxed under PAYE who sells a share portfolio. GOV.UK’s list of who must send a return also includes anyone who had to pay capital gains tax, so check with HMRC before relying on the real time service alone. If a return is needed, you must tell HMRC by 5 October after the end of the tax year; see registering for Self Assessment.
What do you need before you start?
GOV.UK lists the information required for each gain or loss:
- what you paid for the asset and what you sold it for;
- the dates you acquired and disposed of it;
- costs of buying, selling or improving it, and any reliefs you are claiming;
- a calculation for each gain or loss.
You must attach a copy of your calculations when you report.
How does this look in practice?
Illustration only. Tom is employed with taxable income of £20,000 after his personal allowance. In June 2026 he sells shares and makes a gain of £13,000. He has no other disposals in 2026 to 2027 and no losses.
- Taxable gain: £13,000 less the £3,000 annual exempt amount, which is £10,000.
- Income plus gain is £30,000, within the £37,700 basic rate band for 2026 to 2027, so the whole £10,000 is taxed at 18%.
- Tax due: £1,800, which he can report through the real time service at any point up to 31 December 2027.
- He must pay by 31 January 2028 using the X reference HMRC sends him.
Had his income been higher, part or all of the gain would be taxed at 24%. See capital gains tax rates.
What mistakes come up most often?
- Using the real time service for a UK residential property sale, which belongs on the 60 day return.
- Agents trying to file on a client’s behalf, which the service does not allow.
- Leaving the gain off a Self Assessment return because it was already reported in real time.
- Paying with the wrong reference number, so the money is allocated to another bill.
- Missing the 31 December reporting date while still paying on time.
If HMRC opens a check into your return, tax investigation insurance pays your accountant’s fees. Solar Protect cover pays up to £100,000 with no excess; it never pays tax, interest or penalties. Read how our cover works or get a quote.
Related Accountapedia entries
- Income tax and CGT during estate administration
- Non resident capital gains tax on UK property
- Claiming and using capital losses
- Who needs to file a Self Assessment tax return
- Selling a second home: capital gains tax
- SA302 tax calculations and tax year overviews
- Record keeping rules for the self employed
Sources
- GOV.UK: If you have other capital gains to report
- GOV.UK: Report and pay your capital gains tax
- GOV.UK: Ways to pay
- GOV.UK: Reporting and paying capital gains tax
- GOV.UK: Work out need to pay
- GOV.UK: Allowances
- GOV.UK: Rates
- GOV.UK: Losses
- legislation.gov.uk: Act 1970 c. 9, section 59A
- legislation.gov.uk: Act 1970 c. 9, section 59B
Reviewed by Christine Anderson, Broker, Solar Protect. Last reviewed 8 October 2026. Part of Accountapedia, the Solar Protect guide to UK tax and accounting. This page is general information, not personalised advice.