{
  "$comment": "Machine-readable companion to https://valem.run/calculators/uk/car-tax. Formula, inputs, outputs, engine-verified test vectors, cited sources and the re-runnable Valem ModelSpec behind the page.",
  "url": "https://valem.run/calculators/uk/car-tax",
  "dataUrl": "https://valem.run/calculators/uk/car-tax.json",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "United Kingdom vehicle tax model by Valem (https://valem.run/calculators/uk/car-tax), CC BY 4.0.",
    "note": "Covers the model — the expression of each rule and the arrangement of the catalog. The rates and thresholds themselves are law and are not licensed by anyone; the cited sources are where they come from."
  },
  "verificationUrl": "https://valem.run/calculators/uk/car-tax/verify",
  "country": "uk",
  "countryName": "United Kingdom",
  "formula": "car-tax",
  "formulaName": "Vehicle tax",
  "title": "Car Tax Calculator UK — Vehicle Excise Duty (VED)",
  "answer": "UK vehicle tax is a first-year rate set by CO₂ emissions, then a £200 standard rate from year two, plus a £440 supplement for cars listed over £40,000.",
  "lang": "en",
  "currency": "GBP",
  "taxYear": "2026-27",
  "verification": {
    "claim": "internal-consistency",
    "statement": "The Valem engine reproduces this model's stated formula through 2 self-test cases (below, and re-runnable against the spec). That asserts internal consistency, NOT that the formula matches current law — the cited sources are the evidence for that, and carry the date each was last checked.",
    "selfTestCases": 2,
    "ratesAreIllustrative": false,
    "sourcesCheckedOn": "2026-08-02"
  },
  "sources": [
    {
      "label": "GOV.UK — Vehicle tax rate tables",
      "url": "https://www.gov.uk/vehicle-tax-rate-tables",
      "checked": "2026-08-02"
    }
  ],
  "terminalOutput": "standardVED",
  "inputs": [
    {
      "name": "co2",
      "type": "number",
      "label": "CO₂ emissions (g/km)",
      "minimum": 0
    },
    {
      "name": "listPrice",
      "type": "number",
      "label": "List price (GBP)",
      "minimum": 0
    }
  ],
  "outputs": [
    {
      "name": "firstYearVED",
      "type": "number",
      "label": "First-year rate",
      "format": "currency",
      "formula": "($c := co2; $c = 0 ? 10 : $c <= 50 ? 115 : $c <= 75 ? 135 : $c <= 90 ? 280 : $c <= 100 ? 365 : $c <= 110 ? 405 : $c <= 130 ? 455 : $c <= 150 ? 560 : $c <= 170 ? 1410 : $c <= 190 ? 2270 : $c <= 225 ? 3420 : $c <= 255 ? 4850 : 5690)"
    },
    {
      "name": "expensiveSupplement",
      "type": "number",
      "label": "Expensive-car supplement",
      "format": "currency",
      "formula": "listPrice > $const.expensiveThreshold ? $const.expensiveSupplementRate : 0"
    },
    {
      "name": "standardVED",
      "type": "number",
      "label": "Standard rate (year 2+)",
      "format": "currency",
      "formula": "$round($const.standardRate + expensiveSupplement, 2)"
    }
  ],
  "testCases": [
    {
      "description": "C1 petrol 128 g/km, list £30,000",
      "given": {
        "co2": 128,
        "listPrice": 30000
      },
      "expect": {
        "firstYearVED": 455,
        "expensiveSupplement": 0,
        "standardVED": 200
      }
    },
    {
      "description": "C2 190 g/km, list £42,000 — expensive-car supplement",
      "given": {
        "co2": 190,
        "listPrice": 42000
      },
      "expect": {
        "firstYearVED": 2270,
        "expensiveSupplement": 440,
        "standardVED": 640
      }
    }
  ],
  "spec": {
    "id": "car-tax-uk",
    "version": "1.0.0",
    "schema": {
      "type": "object",
      "properties": {
        "co2": {
          "type": "number",
          "minimum": 0
        },
        "listPrice": {
          "type": "number",
          "minimum": 0
        },
        "firstYearVED": {
          "type": "number",
          "readOnly": true
        },
        "expensiveSupplement": {
          "type": "number",
          "readOnly": true
        },
        "standardVED": {
          "type": "number",
          "readOnly": true
        }
      }
    },
    "constants": {
      "standardRate": 200,
      "expensiveThreshold": 40000,
      "expensiveSupplementRate": 440
    },
    "defaultValues": [
      {
        "path": "$",
        "expr": "{ 'co2': 128, 'listPrice': 30000 }"
      }
    ],
    "derivations": [
      {
        "path": "$.firstYearVED",
        "expr": "($c := co2; $c = 0 ? 10 : $c <= 50 ? 115 : $c <= 75 ? 135 : $c <= 90 ? 280 : $c <= 100 ? 365 : $c <= 110 ? 405 : $c <= 130 ? 455 : $c <= 150 ? 560 : $c <= 170 ? 1410 : $c <= 190 ? 2270 : $c <= 225 ? 3420 : $c <= 255 ? 4850 : 5690)"
      },
      {
        "path": "$.expensiveSupplement",
        "expr": "listPrice > $const.expensiveThreshold ? $const.expensiveSupplementRate : 0"
      },
      {
        "path": "$.standardVED",
        "expr": "$round($const.standardRate + expensiveSupplement, 2)"
      }
    ],
    "constraints": [],
    "metaDerivations": [],
    "viewDefinition": {
      "renderer": "builtin",
      "defaultView": "main",
      "views": [
        {
          "id": "main",
          "label": "Vehicle tax",
          "layout": "vertical",
          "components": [
            {
              "id": "co2",
              "type": "numericField",
              "label": "CO₂ emissions (g/km)",
              "bind": "$.co2"
            },
            {
              "id": "listPrice",
              "type": "numericField",
              "label": "List price (GBP)",
              "bind": "$.listPrice"
            },
            {
              "id": "tiles",
              "type": "group",
              "layout": "horizontal",
              "components": [
                {
                  "id": "fyTile",
                  "type": "statTile",
                  "label": "First-year rate",
                  "bind": "$.firstYearVED",
                  "format": "currency",
                  "currency": "GBP"
                },
                {
                  "id": "stdTile",
                  "type": "statTile",
                  "label": "Standard rate (year 2+)",
                  "bind": "$.standardVED",
                  "format": "currency",
                  "currency": "GBP"
                }
              ]
            },
            {
              "id": "sep1",
              "type": "separatorLine"
            },
            {
              "id": "breakdown",
              "type": "keyValueList",
              "label": "Breakdown",
              "items": [
                {
                  "label": "First-year rate (by CO₂)",
                  "bind": "$.firstYearVED",
                  "format": "currency",
                  "currency": "GBP"
                },
                {
                  "label": "Standard rate",
                  "bind": "$.standardVED",
                  "format": "currency",
                  "currency": "GBP"
                },
                {
                  "label": "Expensive-car supplement",
                  "bind": "$.expensiveSupplement",
                  "format": "currency",
                  "currency": "GBP"
                }
              ]
            },
            {
              "id": "note",
              "type": "staticText",
              "text": "'UK VED 2026-27: first-year rate by CO₂ band, then a £200 standard rate plus a £440 expensive-car supplement (years 2-6) for list prices over £40,000 (£50,000 for electric cars registered from 1 April 2026, not modelled here). Estimate, not tax advice.'"
            },
            {
              "id": "sources",
              "type": "sourceList",
              "label": "Sources",
              "items": [
                {
                  "label": "GOV.UK — Vehicle tax rate tables",
                  "url": "https://www.gov.uk/vehicle-tax-rate-tables",
                  "date": "2026-08-02"
                }
              ]
            }
          ]
        }
      ]
    },
    "tests": [
      {
        "description": "C1 petrol 128 g/km, list £30,000",
        "given": {
          "$.co2": 128,
          "$.listPrice": 30000
        },
        "expect": {
          "$.firstYearVED": 455,
          "$.expensiveSupplement": 0,
          "$.standardVED": 200
        }
      },
      {
        "description": "C2 190 g/km, list £42,000 — expensive-car supplement",
        "given": {
          "$.co2": 190,
          "$.listPrice": 42000
        },
        "expect": {
          "$.firstYearVED": 2270,
          "$.expensiveSupplement": 440,
          "$.standardVED": 640
        }
      }
    ]
  }
}