Explore More Capital Gains Tax Calculators
Why Combining Matters
Every CGT calculator checked when building this site — including dedicated property, shares and crypto tools — calculates each asset type in isolation. That's wrong for anyone who disposed of more than one type of asset in the same tax year: the £3,000 annual exempt amount is a single allowance per person, per tax year, not one per asset type. Run a property sale through one calculator and a share sale through another, and you'll double-count the allowance and get a wrong total.
How HMRC actually assesses combined gains
On your Self Assessment CGT summary, you report all chargeable gains for the year together. HMRC's guidance allows the annual exempt amount and remaining basic rate band to be set against whichever gains reduce your tax bill the most — in practice, that means applying the allowance to gains taxed at the standard 18%/24% rates before gains already benefiting from a lower flat rate (such as Business Asset Disposal Relief), since the allowance saves more tax there.
| Step | What happens |
|---|---|
| 1 | Sum all chargeable gains (and losses) across every disposal in the tax year |
| 2 | Apply the single £3,000 exempt amount — to standard-rate gains first, then BADR gains if any allowance remains |
| 3 | Fill your remaining basic rate Income Tax band with standard-rate taxable gains at 18%, the rest at 24% |
| 4 | Tax any remaining BADR-qualifying gain at a flat 18% |
This is a simplified model of that ordering — it doesn't cover carried interest, Investors' Relief, or gains eligible for multiple different reliefs at once. For anything beyond a straightforward mix of property/shares/crypto/business gains, confirm the exact ordering with an accountant.
How this calculator works — Formulas & Method
Source: gov.uk/capital-gains-tax/rates, HS284 Shares and Capital Gains Tax (allowance/band ordering) · Deterministic calculation — no AI, no arbitrary estimation
Constants used
| Constant | Value | Source |
|---|---|---|
| Annual exempt amount | £3,000 (single, shared across all disposals) | gov.uk/capital-gains-tax/rates, 2026/27 |
| Basic rate band upper limit | £50,270 taxable income (single, shared) | gov.uk Income Tax rates 2026/27 |
| CGT basic / higher rate | 18% / 24% | gov.uk/capital-gains-tax/rates |
| BADR rate | 18%, £1m lifetime limit | gov.uk/business-asset-disposal-relief |
Formulas
gains_nonbadr = sum of all non-BADR disposal gains/losses, floored at 0
gains_badr = sum of all BADR-qualifying disposal gains, floored at 0
— Allocate ONE shared £3,000 allowance —
exempt_nonbadr = min(£3,000, gains_nonbadr) (applied first — saves more tax)
exempt_badr = min(£3,000 − exempt_nonbadr, gains_badr)
— Allocate ONE shared basic-rate band —
basic_band_remaining = max(0, £50,270 − other_taxable_income)
at_18pct = min(gains_nonbadr − exempt_nonbadr, basic_band_remaining)
at_24pct = (gains_nonbadr − exempt_nonbadr) − at_18pct
cgt = at_18pct × 18% + at_24pct × 24% + (gains_badr − exempt_badr) × 18%
Deterministic calculation based on official 2026/27 bands. Simplified model of HMRC's "most beneficial" ordering rule — doesn't cover carried interest, Investors' Relief, or losses carried forward from prior years; always confirm your own position with HMRC or a qualified adviser.
Get It Filed Correctly, Not Just Estimated
This calculator gives an estimate — actually reporting and paying it correctly is a separate step with its own deadline and paperwork.
- Mixed disposals in one tax year: a property sale on top of a share sale doesn't just add two bills together — the deadlines differ (60 days for property, 31 January Self Assessment for everything else) and the order gains are set against your allowance and rate bands changes what you owe. Getting the sequencing wrong is a common source of overpayment.
- Multiple disposals in one tax year: ordering and timing disposals across the 5/6 April boundary can materially change what you owe.
- Inherited or gifted assets: your acquisition cost for CGT purposes isn't always what you think — get the base cost confirmed.
- Business Asset Disposal Relief: can cut your rate to 18% on qualifying gains, but eligibility rules are strict.
A fixed-fee online accountant can handle the return and your wider Self Assessment together.
Compare Online Accountants →Transparency & Methodology
Methodology & Sources
Figures are public HMRC rates. For your exact position, use gov.uk/capital-gains-tax.
Not Tax or Legal Advice
Information only. Consult the Chartered Institute of Taxation or an adviser via the FCA Register.
Open Source
Formulas are public. Inspect on GitHub.