Guide
Report capital gains on your Self Assessment
How to report capital gains using SA108, including the annual exempt amount, CGT rates, the 60-day residential property reporting rule, key reliefs, and how to offset losses.
You must report capital gains to HMRC when you dispose of an asset and make a profit (a "gain"). Disposals include selling, gifting, swapping, or receiving compensation for an asset. This guide covers how to report those gains through Self Assessment.
What counts as a disposal
You may need to report a gain on:
- Shares and investments - selling or transferring shares, unit trusts, or other securities
- Residential property - selling a second home, buy-to-let, or inherited property (not your main home if Private Residence Relief applies)
- Business assets - selling equipment, premises, goodwill, or intellectual property
- Land - selling or part-disposing of land
- Crypto assets - selling, exchanging, or gifting cryptocurrency
- Gifts above market value - HMRC treats gifts of assets as disposals at market value
Not taxable: Your main home (usually), ISA investments, gilts, premium bond prizes, personal possessions worth under £6,000, and transfers between spouses or civil partners.
Annual exempt amount
Each tax year you can make gains up to the annual exempt amount before CGT is due. Only gains above this threshold are taxable. If your total gains for the year (after deducting allowable costs and any losses) fall within the exempt amount, you may not need to report at all.
How CGT rates are determined
The rate you pay depends on two things: the type of asset and your total taxable income for the year.
To work out which rate applies:
- Calculate your total taxable income (employment, self-employment, rental, etc.)
- Deduct your Personal Allowance (currently £12,570)
- Check how much of the basic rate band (up to £50,270 for 2025/26) remains unused
- Gains that fall within the remaining basic rate band are taxed at the lower rate
- Gains that exceed the remaining basic rate band are taxed at the higher rate
Example: Your taxable income is £40,000. After the Personal Allowance, you have used £27,430 of the basic rate band. You have £22,840 of basic rate band remaining. If your taxable gain (after the exempt amount) is £30,000, the first £22,840 is taxed at the lower rate and the remaining £7,160 at the higher rate.
60-day reporting for residential property
If you sell or dispose of UK residential property that is not fully covered by Private Residence Relief, you must report and pay CGT within 60 days of completion. This applies even if you also need to include the gain on your Self Assessment return.
You report through a separate online service - the Capital Gains Tax on UK property account. If you have already paid CGT through the 60-day service, that payment is credited against your Self Assessment bill so you do not pay twice.
What triggers the 60-day rule:
- Selling a buy-to-let property
- Selling a second home
- Selling an inherited property you did not live in
- Selling your home where only partial Private Residence Relief applies
Late reporting penalties: The same penalty structure as late Self Assessment applies - £100 initial penalty, escalating for continued delay.
Reporting on SA108
For assets other than UK residential property (or in addition to a 60-day report), you report capital gains on the SA108 supplementary pages of your Self Assessment return.
Sections of SA108 you may need to complete
- Listed shares and securities - shares traded on a recognised stock exchange
- Unlisted shares and securities - private company shares
- Property and other assets - land, business assets, crypto assets, personal possessions over £6,000
- Capital gains summary - total gains, losses, exempt amount, and tax due
Calculating your gain
For each disposal, work out:
- Disposal proceeds - the amount you received (or market value for gifts)
- Minus allowable costs - original purchase price, buying and selling costs (solicitor fees, stamp duty, estate agent fees), improvement costs (but not maintenance)
- Equals gain or loss - the difference is your chargeable gain (or allowable loss)
For shares, use the share identification rules (same-day, 30-day, section 104 pool) to determine which shares you are disposing of and their cost basis.
Key reliefs
Several reliefs can reduce or eliminate CGT. You must claim these on your return - they are not applied automatically.
Private Residence Relief (PRR)
Exempts gains on the sale of your main home. Applies automatically if you lived in the property as your only or main home throughout the entire period of ownership. Partial relief applies if you lived there for part of the time or used part of the property exclusively for business.
Business Asset Disposal Relief (BADR)
Reduces the CGT rate to 14% (2025/26) on qualifying business disposals up to a £1,000,000 lifetime limit. The rate rises to 18% from April 2026. You qualify if you are disposing of all or part of a business you have owned for at least two years, or shares in your personal trading company where you hold at least 5% and are an officer or employee.
Investors' Relief
Similar to BADR but for external investors. Applies to shares in unlisted trading companies subscribed for after 17 March 2016 and held for at least three years. The same reduced rate (14% in 2025/26, rising to 18% from April 2026) and £1,000,000 lifetime limit apply.
Other reliefs
- Gift Hold-Over Relief - defer CGT when gifting business assets or shares in unlisted trading companies
- Rollover Relief - defer CGT when you sell a business asset and reinvest the proceeds in a new qualifying asset within three years
- EIS/SEIS deferral relief - defer CGT by investing gains into qualifying Enterprise Investment Scheme or Seed EIS companies
Losses
Capital losses can reduce your CGT bill. Understanding how to use them is important:
- Current year losses - must be set against gains in the same tax year first, even if this wastes your annual exempt amount
- Brought forward losses - losses from previous years can be carried forward indefinitely and used to reduce gains below the annual exempt amount
- Reporting losses - you must report losses to HMRC within four years of the end of the tax year in which they arose to use them later
Important: Losses from disposals to connected persons (family members, business partners) can only be set against gains from disposals to the same connected person. Losses on assets that qualify for EIS income tax relief cannot be used as capital losses.
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1. Identify all disposals in the tax year
List every asset you sold, gifted, or exchanged between 6 April and 5 April. Include shares, property, business assets, and crypto assets.
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2. Report residential property within 60 days
If you sold UK residential property not fully covered by Private Residence Relief, report and pay CGT within 60 days of completion using the Capital Gains Tax on UK property account on GOV.UK.
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3. Calculate each gain or loss
For each disposal, subtract your allowable costs (purchase price, buying/selling costs, improvement costs) from the disposal proceeds. Apply share identification rules for share disposals.
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4. Apply reliefs and the annual exempt amount
Claim any applicable reliefs (BADR, PRR, Rollover Relief). Deduct current year losses, then apply the annual exempt amount to reduce taxable gains.
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5. Determine your CGT rate
Work out how much of your basic rate band remains after your other income. Gains within the remaining band are taxed at the lower rate; gains above at the higher rate.
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6. Complete SA108 on your Self Assessment return
Log in to HMRC's Self Assessment service and complete the capital gains supplementary pages (SA108). Enter each disposal, any reliefs claimed, and losses.
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7. Submit by 31 January and pay any CGT due
File your return online and pay the CGT liability. If you already paid through a 60-day property report, this amount is credited against your bill.