{
  "$comment": "Machine-readable companion to https://valem.run/calculators/australia/vat. Formula, inputs, outputs, engine-verified test vectors, cited sources and the re-runnable Valem ModelSpec behind the page.",
  "url": "https://valem.run/calculators/australia/vat",
  "dataUrl": "https://valem.run/calculators/australia/vat.json",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Australia gst model by Valem (https://valem.run/calculators/australia/vat), 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/australia/vat/verify",
  "country": "australia",
  "countryName": "Australia",
  "formula": "vat",
  "formulaName": "GST",
  "title": "GST Calculator Australia 2026 — Add or Remove 10%",
  "answer": "Australian GST is 10%, fixed by section 9-70 of the GST Act 1999. Because the rate is a tenth, the GST inside a GST-inclusive price is exactly one eleventh of it.",
  "lang": "en",
  "currency": "AUD",
  "taxYear": "2026",
  "verification": {
    "claim": "internal-consistency",
    "statement": "The Valem engine reproduces this model's stated formula through 4 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": 4,
    "ratesAreIllustrative": false,
    "sourcesCheckedOn": "2026-10-05"
  },
  "sources": [
    {
      "label": "Federal Register of Legislation - GST Act 1999 s 9-70 (10%)",
      "url": "https://www.legislation.gov.au/C2004A00446/latest/text",
      "checked": "2026-10-05"
    }
  ],
  "terminalOutput": "grossAmount",
  "headlineOutput": "vatAmount",
  "inputs": [
    {
      "name": "amount",
      "type": "number",
      "label": "Amount",
      "minimum": 0
    },
    {
      "name": "direction",
      "type": "string",
      "label": "Direction",
      "enum": [
        "add",
        "remove"
      ]
    },
    {
      "name": "reverseCharge",
      "type": "boolean",
      "label": "B2B reverse charge applies"
    }
  ],
  "outputs": [
    {
      "name": "rate",
      "type": "number",
      "formula": "$const.standardRate"
    },
    {
      "name": "effectiveRate",
      "type": "number",
      "formula": "reverseCharge ? 0 : rate"
    },
    {
      "name": "netAmount",
      "type": "number",
      "formula": "direction = 'remove' ? $round(amount / (1 + effectiveRate), 2) : $round(amount, 2)"
    },
    {
      "name": "vatAmount",
      "type": "number",
      "formula": "$round(netAmount * effectiveRate, 2)"
    },
    {
      "name": "grossAmount",
      "type": "number",
      "formula": "$round(netAmount + vatAmount, 2)"
    }
  ],
  "testCases": [
    {
      "description": "S1 100.00 AUD net at 10%",
      "given": {
        "amount": 100,
        "direction": "add",
        "reverseCharge": false
      },
      "expect": {
        "vatAmount": 10,
        "grossAmount": 110,
        "netAmount": 100
      }
    },
    {
      "description": "S2 110.00 AUD gross back to net: GST is one eleventh",
      "given": {
        "amount": 110,
        "direction": "remove",
        "reverseCharge": false
      },
      "expect": {
        "netAmount": 100,
        "vatAmount": 10
      }
    },
    {
      "description": "S3 reverse charge: the supplier charges no GST",
      "given": {
        "amount": 100,
        "direction": "add",
        "reverseCharge": true
      },
      "expect": {
        "vatAmount": 0,
        "grossAmount": 100
      }
    },
    {
      "description": "S4 a 2 200.00 AUD invoice holds 200.00 of GST",
      "given": {
        "amount": 2200,
        "direction": "remove",
        "reverseCharge": false
      },
      "expect": {
        "netAmount": 2000,
        "vatAmount": 200
      }
    }
  ],
  "spec": {
    "id": "vat-australia",
    "version": "1.0.0",
    "schema": {
      "type": "object",
      "properties": {
        "amount": {
          "type": "number",
          "minimum": 0
        },
        "direction": {
          "type": "string",
          "enum": [
            "add",
            "remove"
          ]
        },
        "reverseCharge": {
          "type": "boolean"
        },
        "rate": {
          "type": "number",
          "readOnly": true
        },
        "effectiveRate": {
          "type": "number",
          "readOnly": true
        },
        "netAmount": {
          "type": "number",
          "readOnly": true
        },
        "vatAmount": {
          "type": "number",
          "readOnly": true
        },
        "grossAmount": {
          "type": "number",
          "readOnly": true
        }
      }
    },
    "constants": {
      "standardRate": 0.1
    },
    "defaultValues": [
      {
        "path": "$",
        "expr": "{ 'amount': 100, 'direction': 'add', 'reverseCharge': false }"
      }
    ],
    "derivations": [
      {
        "path": "$.rate",
        "expr": "$const.standardRate"
      },
      {
        "path": "$.effectiveRate",
        "expr": "reverseCharge ? 0 : rate"
      },
      {
        "path": "$.netAmount",
        "expr": "direction = 'remove' ? $round(amount / (1 + effectiveRate), 2) : $round(amount, 2)"
      },
      {
        "path": "$.vatAmount",
        "expr": "$round(netAmount * effectiveRate, 2)"
      },
      {
        "path": "$.grossAmount",
        "expr": "$round(netAmount + vatAmount, 2)"
      }
    ],
    "constraints": [],
    "viewDefinition": {
      "renderer": "builtin",
      "defaultView": "main",
      "views": [
        {
          "id": "main",
          "label": "VAT",
          "layout": "vertical",
          "components": [
            {
              "id": "note",
              "type": "staticText",
              "text": "Australia has a single GST rate of 10%, fixed by section 9-70 of the A New Tax System (Goods and Services Tax) Act 1999: \"The amount of GST on a taxable supply is 10% of the value of the taxable supply.\" Because the rate is a tenth, the GST inside a GST-inclusive price is exactly one eleventh of it. GST-free supplies - most basic food, health and education - carry no GST at all, which is a different mechanism from a reduced rate and so is not offered here as a band. This page covers the RATE only: the Act creates a registration turnover threshold at section 23-15 but leaves the figure to regulations, so the 75 000 AUD commonly quoted is not established by the Act and the ATO refuses non-interactive requests. It is omitted rather than taken on trust."
            },
            {
              "id": "inputs",
              "type": "fieldSet",
              "label": "Your figures",
              "components": [
                {
                  "id": "amount",
                  "type": "numericField",
                  "label": "Amount",
                  "bind": "$.amount",
                  "helperText": "Net amount when adding VAT, gross amount when removing it."
                },
                {
                  "id": "direction",
                  "type": "selectField",
                  "label": "Direction",
                  "bind": "$.direction",
                  "options": [
                    {
                      "value": "add",
                      "label": "Add VAT (net → gross)"
                    },
                    {
                      "value": "remove",
                      "label": "Remove VAT (gross → net)"
                    }
                  ]
                },
                {
                  "id": "reverseCharge",
                  "type": "checkboxField",
                  "label": "B2B reverse charge applies",
                  "bind": "$.reverseCharge",
                  "helperText": "The customer accounts for the VAT, so you charge none."
                }
              ]
            },
            {
              "id": "sep",
              "type": "separatorLine"
            },
            {
              "id": "vatTile",
              "type": "statTile",
              "label": "VAT",
              "value": "$.vatAmount"
            },
            {
              "id": "netTile",
              "type": "statTile",
              "label": "Net",
              "value": "$.netAmount"
            },
            {
              "id": "grossTile",
              "type": "statTile",
              "label": "Gross",
              "value": "$.grossAmount"
            },
            {
              "id": "breakdown",
              "type": "keyValueList",
              "label": "Detail",
              "items": [
                {
                  "label": "Rate applied",
                  "value": "$.effectiveRate"
                },
                {
                  "label": "Statutory rate",
                  "value": "$.rate"
                }
              ]
            },
            {
              "id": "sources",
              "type": "sourceList",
              "label": "Sources",
              "layers": 1,
              "items": [
                {
                  "label": "Federal Register of Legislation - GST Act 1999 s 9-70 (10%)",
                  "url": "https://www.legislation.gov.au/C2004A00446/latest/text",
                  "date": "2026-10-05",
                  "covers": [
                    "standardRate"
                  ]
                }
              ]
            }
          ]
        }
      ]
    },
    "tests": [
      {
        "description": "S1 100.00 AUD net at 10%",
        "given": {
          "$.amount": 100,
          "$.direction": "add",
          "$.reverseCharge": false
        },
        "expect": {
          "$.vatAmount": 10,
          "$.grossAmount": 110,
          "$.netAmount": 100
        }
      },
      {
        "description": "S2 110.00 AUD gross back to net: GST is one eleventh",
        "given": {
          "$.amount": 110,
          "$.direction": "remove",
          "$.reverseCharge": false
        },
        "expect": {
          "$.netAmount": 100,
          "$.vatAmount": 10
        }
      },
      {
        "description": "S3 reverse charge: the supplier charges no GST",
        "given": {
          "$.amount": 100,
          "$.direction": "add",
          "$.reverseCharge": true
        },
        "expect": {
          "$.vatAmount": 0,
          "$.grossAmount": 100
        }
      },
      {
        "description": "S4 a 2 200.00 AUD invoice holds 200.00 of GST",
        "given": {
          "$.amount": 2200,
          "$.direction": "remove",
          "$.reverseCharge": false
        },
        "expect": {
          "$.netAmount": 2000,
          "$.vatAmount": 200
        }
      }
    ]
  }
}