Report capital gains on your Self Assessment

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:

1. Calculate your total taxable income (employment, self-employment, rental, etc.)
2. Deduct your Personal Allowance (currently £12,570)
3. Check how much of the basic rate band (up to £50,270 for 2026/27) remains unused
4. Gains that fall within the remaining basic rate band are taxed at the lower rate
5. 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:

1. Disposal proceeds - the amount you received (or market value for gifts)
2. Minus allowable costs - original purchase price, buying and selling costs (solicitor fees, stamp duty, estate agent fees), improvement costs (but not maintenance)
3. 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 18% (2026/27) on qualifying business disposals up to a £1,000,000 lifetime limit (the rate was 14% in 2025/26). 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 (18% for 2026/27) 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.