Capital Gains Tax Calculator
This simplified calculator allocates taxable gains across the remaining basic-rate band. It does not model every relief, loss rule, residential-property reporting rule or special rate.
Quick answer
The estimate deducts entered losses and the £3,000 annual exempt amount, then applies 18% within the remaining basic band and 24% above it.
Calculator
How to use this calculator
- Enter the figures that match your current scenario.
- Check the effective date, assumptions and any jurisdiction or plan selection.
- Review the breakdown, test a second scenario and verify the result before acting.
Explanation
What it is
The estimate deducts entered losses and the £3,000 annual exempt amount, then applies 18% within the remaining basic band and 24% above it.
How it works
The method deducts losses and the annual exempt amount, determines how much of the £37,700 basic band remains after other taxable income, and splits the gain between 18% and 24%.
When to use it
Use this tool to explore a planning scenario before checking current official rules, product documents or professional guidance.
Limitations
- The result is an estimate based only on the inputs shown.
- Rates, thresholds and product terms can change after the effective date.
- The calculator does not replace an official assessment, provider quote or personalised advice.
Key terms
- Estimate
- A planning result produced from the stated inputs and assumptions, not a guaranteed outcome.
- Effective date
- The date or tax year for which a changing rule, threshold or rate has been checked.
- Authoritative source
- An official or regulator-backed source used to support a rule, rate or calculation method.
Formula
How we calculate this
The method deducts losses and the annual exempt amount, determines how much of the £37,700 basic band remains after other taxable income, and splits the gain between 18% and 24%.
Statutory or methodological reference:GOV.UK official guidance — Capital Gains Tax.
Formula trace: Gain = proceeds minus allowable costs and reliefs; apply annual exempt amount and rate based on asset type and taxable income; handle losses and tax year.
Worked example
Enter realistic figures into the capital gains tax calculator and compare the result with the breakdown. Change one assumption at a time so you can see which factor has the greatest effect. Check the governing rule at GOV.UK official guidance — Capital Gains Tax.
FAQ
What does the capital gains tax calculator calculate?
The estimate deducts entered losses and the £3,000 annual exempt amount, then applies 18% within the remaining basic band and 24% above it.
Which assumptions have the biggest effect?
The most important assumptions are the amounts, time period, applicable rate or threshold, and any jurisdiction or plan choice shown in the form.
How accurate is this estimate?
It is designed for planning and testing scenarios. Accuracy depends on the inputs and whether your circumstances fit the simplified method described on the page.
Can I use the result as a final decision?
No. Verify changing rules and product terms, and seek suitable professional or official guidance when the decision is material or complex.
When should I recalculate?
Recalculate after a change in income, balance, rate, term, household circumstances, tax year or official policy.
Common mistakes
- Using a headline rate without checking whether it applies to the full amount.
- Mixing monthly and annual figures.
- Treating an educational estimate as an official assessment or guaranteed quote.
Tips
- Test a cautious scenario as well as an optimistic one.
- Keep a note of the assumptions and effective date.
- Compare the result with official guidance or provider documents before acting.
Related calculators
Related guides
Sources and editorial review
- GOV.UK official guidance — Capital Gains Tax
- GOV.UK official guidance — Rates
- GOV.UK official guidance — Tax Sell Property
Author and review
Author: FinanceHub UK Editorial Team — Editorial. Editorial policy.
Reviewed by role: Chartered tax adviser. Named qualified reviewer sign-off is pending before production.
Review record date: 2026-07-10. Next review due: 2027-03-01.