/compute/capital-gains-uk

Base URL https://api.babylon.app/v1

POST `/compute/capital-gains-uk`

Compute capital gains for an HMRC tax year. The calculation excludes ISA and SIPP accounts and excludes UK gilts.

JSON request body

segmentLedger (required) — segment-ledger identifier.
taxYear (required) — tax year such as 2024/25 or 2024/2025.
valueDate (optional) — valuation date in YYYY-MM-DD format; defaults to the current date.
target (optional) — CapitalGains (default), ExplainGains or ExcelExplain.

Example request

POST /compute/capital-gains-uk
Content-Type: application/json

{
  "segmentLedger": "MyGBSegment",
  "taxYear": "2024/25",
  "valueDate": "2025-04-05"
}

Example response — 200

The default CapitalGains target returns a table.

{
  "name": "CapitalGains",
  "description": "Capital gains on ledger MyGBSegment under HMRC for tax year 2024/25.",
  "columns": ["accountAlias", "accountType", "bourseSymbol", "isin", "securityType", "description", "tradeDate", "settleDate", "costBasis", "netProceeds", "capitalGain", "currency", "capitalGainInBase", "baseCurrency", "taxYear", "taxAuthority"],
  "columnTypes": {
    "costBasis": "Decimal",
    "netProceeds": "Decimal",
    "capitalGain": "Decimal",
    "capitalGainInBase": "Decimal"
  },
  "rows": [
    {
      "accountAlias": "Broker-GIA",
      "accountType": "GIA",
      "bourseSymbol": "LSE:VOD",
      "isin": "GB00BH4HKS39",
      "securityType": "SHRS",
      "description": "Vodafone Group PLC",
      "tradeDate": "2024-10-01",
      "settleDate": "2024-10-03",
      "costBasis": "900.00",
      "netProceeds": "1100.00",
      "capitalGain": "200.00",
      "currency": "GBP",
      "capitalGainInBase": "200.00",
      "baseCurrency": "GBP",
      "taxYear": "2024/25",
      "taxAuthority": "HMRC"
    }
  ]
}

ExplainGains returns a JSON array of per-security calculation tables. ExcelExplain returns a drill-down report in JSON, or an XLSX workbook when requested with Accept: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.

The default table can be requested as CSV with Accept: text/csv.

GET `/compute/capital-gains-uk`

GET supplies the same operation parameters in the query string.

GET /compute/capital-gains-uk?segmentLedger=MyGBSegment&taxYear=2024%2F25&valueDate=2025-04-05

The response depends on target in the same way as the POST response.

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