{
  "$comment": "Machine-readable companion to https://valem.run/calculators/singapore/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/singapore/car-tax",
  "dataUrl": "https://valem.run/calculators/singapore/car-tax.json",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Singapore road tax model by Valem (https://valem.run/calculators/singapore/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/singapore/car-tax/verify",
  "country": "singapore",
  "countryName": "Singapore",
  "formula": "car-tax",
  "formulaName": "Road tax",
  "title": "Road Tax Calculator Singapore — by engine cc",
  "answer": "Singapore's road tax for petrol cars is a formula by engine capacity, billed every six months.",
  "lang": "en",
  "currency": "SGD",
  "taxYear": "2026",
  "verification": {
    "claim": "internal-consistency",
    "statement": "The Valem engine reproduces this model's stated formula through 3 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": 3,
    "ratesAreIllustrative": false,
    "sourcesCheckedOn": "2026-08-02"
  },
  "sources": [
    {
      "label": "OneMotoring road tax calculator",
      "url": "https://onemotoring.lta.gov.sg",
      "checked": "2026-08-05"
    }
  ],
  "terminalOutput": "tax",
  "inputs": [
    {
      "name": "cc",
      "type": "number",
      "label": "Engine capacity (cc)",
      "minimum": 0
    },
    {
      "name": "ageYears",
      "type": "number",
      "label": "Vehicle age (years)",
      "minimum": 0
    }
  ],
  "outputs": [
    {
      "name": "baseSixMonth",
      "type": "number",
      "label": "Base 6-monthly road tax",
      "format": "currency",
      "formula": "($c := cc; $b := $c <= 600 ? 200 : $c <= 1000 ? 200 + 0.125 * ($c - 600) : $c <= 1600 ? 250 + 0.375 * ($c - 1000) : $c <= 3000 ? 475 + 0.75 * ($c - 1600) : 1525 + 1.0 * ($c - 3000); $round($b * $const.rebateFactor, 2))"
    },
    {
      "name": "ageSurcharge",
      "type": "number",
      "label": "Age surcharge",
      "formula": "($a := ageYears; $a < 10 ? 0 : $a < 11 ? 0.10 : $a < 12 ? 0.20 : $a < 13 ? 0.30 : $a < 14 ? 0.40 : 0.50)"
    },
    {
      "name": "sixMonth",
      "type": "number",
      "label": "6-monthly payable",
      "format": "currency",
      "formula": "$round(baseSixMonth * (1 + ageSurcharge), 2)"
    },
    {
      "name": "tax",
      "type": "number",
      "label": "Annual road tax",
      "format": "currency",
      "formula": "$round(sixMonth * 2, 2)"
    }
  ],
  "testCases": [
    {
      "description": "C1 1,598 cc sedan, 3 years old — the worked LTA example",
      "given": {
        "cc": 1598,
        "ageYears": 3
      },
      "expect": {
        "baseSixMonth": 370.86,
        "ageSurcharge": 0,
        "sixMonth": 370.86,
        "tax": 741.72
      }
    },
    {
      "description": "C2 same car at 12 years — 30% age surcharge",
      "given": {
        "cc": 1598,
        "ageYears": 12
      },
      "expect": {
        "ageSurcharge": 0.3,
        "sixMonth": 482.12,
        "tax": 964.24
      }
    },
    {
      "description": "C3 small 600 cc car — the flat bottom band",
      "given": {
        "cc": 600,
        "ageYears": 2
      },
      "expect": {
        "baseSixMonth": 156.4,
        "tax": 312.8
      }
    }
  ],
  "spec": {
    "id": "car-tax-singapore",
    "version": "1.0.0",
    "schema": {
      "type": "object",
      "properties": {
        "cc": {
          "type": "number",
          "minimum": 0
        },
        "ageYears": {
          "type": "number",
          "minimum": 0
        },
        "baseSixMonth": {
          "type": "number",
          "readOnly": true
        },
        "ageSurcharge": {
          "type": "number",
          "readOnly": true
        },
        "sixMonth": {
          "type": "number",
          "readOnly": true
        },
        "tax": {
          "type": "number",
          "readOnly": true
        }
      }
    },
    "constants": {
      "rebateFactor": 0.782
    },
    "defaultValues": [
      {
        "path": "$",
        "expr": "{ 'cc': 1598, 'ageYears': 3 }"
      }
    ],
    "derivations": [
      {
        "path": "$.baseSixMonth",
        "expr": "($c := cc; $b := $c <= 600 ? 200 : $c <= 1000 ? 200 + 0.125 * ($c - 600) : $c <= 1600 ? 250 + 0.375 * ($c - 1000) : $c <= 3000 ? 475 + 0.75 * ($c - 1600) : 1525 + 1.0 * ($c - 3000); $round($b * $const.rebateFactor, 2))"
      },
      {
        "path": "$.ageSurcharge",
        "expr": "($a := ageYears; $a < 10 ? 0 : $a < 11 ? 0.10 : $a < 12 ? 0.20 : $a < 13 ? 0.30 : $a < 14 ? 0.40 : 0.50)"
      },
      {
        "path": "$.sixMonth",
        "expr": "$round(baseSixMonth * (1 + ageSurcharge), 2)"
      },
      {
        "path": "$.tax",
        "expr": "$round(sixMonth * 2, 2)"
      }
    ],
    "constraints": [],
    "metaDerivations": [],
    "viewDefinition": {
      "renderer": "builtin",
      "defaultView": "main",
      "views": [
        {
          "id": "main",
          "label": "Road tax",
          "layout": "vertical",
          "components": [
            {
              "id": "cc",
              "type": "numericField",
              "label": "Engine capacity (cc)",
              "bind": "$.cc"
            },
            {
              "id": "age",
              "type": "numericField",
              "label": "Vehicle age (years)",
              "bind": "$.ageYears"
            },
            {
              "id": "tiles",
              "type": "group",
              "layout": "horizontal",
              "components": [
                {
                  "id": "taxTile",
                  "type": "statTile",
                  "label": "Annual road tax",
                  "bind": "$.tax",
                  "format": "currency",
                  "currency": "SGD"
                }
              ]
            },
            {
              "id": "breakdown",
              "type": "keyValueList",
              "label": "Breakdown",
              "items": [
                {
                  "label": "Base 6-monthly road tax",
                  "bind": "$.baseSixMonth",
                  "format": "currency",
                  "currency": "SGD"
                },
                {
                  "label": "Age surcharge",
                  "bind": "$.ageSurcharge"
                },
                {
                  "label": "6-monthly payable",
                  "bind": "$.sixMonth",
                  "format": "currency",
                  "currency": "SGD"
                },
                {
                  "label": "Annual",
                  "bind": "$.tax",
                  "format": "currency",
                  "currency": "SGD"
                }
              ]
            },
            {
              "id": "note",
              "type": "staticText",
              "text": "'Singapore 2026: the LTA 6-monthly road tax formula by engine capacity — 200 up to 600 cc; 200 + 0.125 per cc to 1,000; 250 + 0.375 per cc to 1,600; 475 + 0.75 per cc to 3,000; 1,525 + 1.00 per cc above — all multiplied by the 0.782 rebate factor, then doubled for the annual figure. Cars over 10 years old pay a surcharge rising from 10% to 50%. Diesel and electric vehicles pay on a different basis. Estimate, not tax advice.'"
            },
            {
              "id": "sources",
              "type": "sourceList",
              "label": "Sources",
              "items": [
                {
                  "label": "OneMotoring road tax calculator",
                  "url": "https://onemotoring.lta.gov.sg",
                  "date": "2026-08-05"
                }
              ]
            }
          ]
        }
      ]
    },
    "tests": [
      {
        "description": "C1 1,598 cc sedan, 3 years old — the worked LTA example",
        "given": {
          "$.cc": 1598,
          "$.ageYears": 3
        },
        "expect": {
          "$.baseSixMonth": 370.86,
          "$.ageSurcharge": 0,
          "$.sixMonth": 370.86,
          "$.tax": 741.72
        }
      },
      {
        "description": "C2 same car at 12 years — 30% age surcharge",
        "given": {
          "$.cc": 1598,
          "$.ageYears": 12
        },
        "expect": {
          "$.ageSurcharge": 0.3,
          "$.sixMonth": 482.12,
          "$.tax": 964.24
        }
      },
      {
        "description": "C3 small 600 cc car — the flat bottom band",
        "given": {
          "$.cc": 600,
          "$.ageYears": 2
        },
        "expect": {
          "$.baseSixMonth": 156.4,
          "$.tax": 312.8
        }
      }
    ]
  }
}