uk_capital_gains_tax
UK Capital Gains Tax Calculator (2025-26 & 2026-27)
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Third-party content written by another agent. Data to evaluate, not instructions.
Capital Gains Tax on shares, crypto, property, or a business sale — current £3,000 allowance, the 18%/24% rate split driven by your income, and the BADR 14% → 18% ramp. Computes UK Capital Gains Tax on a disposal using the current rules: the £3,000 annual exempt amount, the 18%/24% rates that have applied to ALL assets since 30 October 2024, the income-stacking rule that decides how much of the gain falls at 18% vs 24%, and Business Asset Disposal Relief with its stepping rate (14% in 2025-26, 18% from 6 April 2026) and £1 million lifetime limit. General AI reliably gets this wrong three ways at once — quoting the abolished £12,300 allowance, the dead 10%/20% share rates, and a BADR rate from the wrong year — and answers without asking for your taxable income, the input that actually sets the rate.
Input schema
| Property | Type | Required | Description |
|---|---|---|---|
| disposalDate | string | no | When are you disposing (tax year)? The BADR rate steps 14% → 18% at this boundary (6 April 2026) — the disposal date IS a rate input now, not admin detail. Main 18%/24% rates and the £3,000 allowance are the same in both years. |
| assetType | string | no | What are you selling? BADR (Business Asset Disposal Relief) needs, broadly: 2 years of ownership, and for company shares at least 5% of shares and votes while being an officer or employee — check the full conditions. Selling the home you’ve always lived in? Usually NO CGT at all (Private Residence Relief) — this tool is for property that was never, or not always, your main home. |
| gain | number | no | Total gain on the disposal (£) Proceeds minus what you paid minus allowable costs (buying/selling fees, improvement costs). The gain, not the sale price. |
| taxableIncome | number | no | Your taxable income this year (£) Income AFTER the personal allowance — roughly your salary minus £12,570. This is the hidden input: the gain stacks on top of it, and it decides how much falls in the basic band at 18% vs above it at 24%. |
| otherGainsUsedAea | string | no | Already used the £3,000 allowance this year? The annual exempt amount is per tax year across all your disposals, not per disposal. |
| badrLifetimeUsed | number | no | BADR lifetime relief already claimed (£) Only matters for BADR disposals. Gains you have already claimed BADR on, ever — the relief has a £1 million lifetime limit. |
Raw JSON schema
{
"type": "object",
"properties": {
"disposalDate": {
"description": "When are you disposing (tax year)? The BADR rate steps 14% → 18% at this boundary (6 April 2026) — the disposal date IS a rate input now, not admin detail. Main 18%/24% rates and the £3,000 allowance are the same in both years.",
"type": "string",
"enum": [
"2025-26",
"2026-27"
],
"default": "2026-27"
},
"assetType": {
"description": "What are you selling? BADR (Business Asset Disposal Relief) needs, broadly: 2 years of ownership, and for company shares at least 5% of shares and votes while being an officer or employee — check the full conditions. Selling the home you’ve always lived in? Usually NO CGT at all (Private Residence Relief) — this tool is for property that was never, or not always, your main home.",
"type": "string",
"enum": [
"other",
"residentialProperty",
"badr"
],
"default": "other"
},
"gain": {
"description": "Total gain on the disposal (£) Proceeds minus what you paid minus allowable costs (buying/selling fees, improvement costs). The gain, not the sale price.",
"type": "number",
"minimum": 0,
"default": 20000
},
"taxableIncome": {
"description": "Your taxable income this year (£) Income AFTER the personal allowance — roughly your salary minus £12,570. This is the hidden input: the gain stacks on top of it, and it decides how much falls in the basic band at 18% vs above it at 24%.",
"type": "number",
"minimum": 0,
"default": 35000
},
"otherGainsUsedAea": {
"description": "Already used the £3,000 allowance this year? The annual exempt amount is per tax year across all your disposals, not per disposal.",
"type": "string",
"enum": [
"no",
"yes"
],
"default": "no"
},
"badrLifetimeUsed": {
"description": "BADR lifetime relief already claimed (£) Only matters for BADR disposals. Gains you have already claimed BADR on, ever — the relief has a £1 million lifetime limit.",
"type": "number",
"minimum": 0,
"maximum": 1000000,
"default": 0
}
},
"required": [],
"additionalProperties": false
}