Add Australia GST regime

CHANGELOG.md

@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 
 ## [Unreleased]
 
+### Added
+
+- `au`: Added the Australian GST regime.
+
 ## [v0.309.0] - 2026-04-01
 
 ### Added

data/regimes/au.json

@@ -0,0 +1,112 @@
+{
+  "$schema": "https://gobl.org/draft-0/tax/regime-def",
+  "name": {
+    "en": "Australia"
+  },
+  "description": {
+    "en": "Australia's indirect tax system is administered by the Australian\nTaxation Office (ATO). Goods and Services Tax (GST) applies at a\nstandard rate of 10%. Supplies may also be GST-free (for example, many\nexports) or input-taxed (for example, certain financial supplies and\nresidential rent). In GOBL's generic GST model, GST-free supplies map to\nthe zero key and input-taxed supplies map to the exempt key.\n\nBusinesses are identified by an Australian Business Number (ABN), an\n11-digit identifier used for GST registration and invoicing. Australian\ntax invoices must show the supplier's details and ABN, and invoices of\nAUD 1,000 or more, or self-billed invoices, must also identify the\ncustomer. Electronic invoicing is aligned with the Peppol PINT A-NZ\nspecification."
+  },
+  "sources": [
+    {
+      "title": {
+        "en": "ATO - GST"
+      },
+      "url": "https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst"
+    },
+    {
+      "title": {
+        "en": "ATO - Tax invoices"
+      },
+      "url": "https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/tax-invoices"
+    },
+    {
+      "title": {
+        "en": "Peppol PINT A-NZ BIS"
+      },
+      "url": "https://docs.peppol.eu/poac/aunz/pint-aunz/bis/"
+    },
+    {
+      "title": {
+        "en": "ATO - eInvoicing"
+      },
+      "url": "https://www.ato.gov.au/businesses-and-organisations/invoicing-and-using-accounting-software/einvoicing"
+    }
+  ],
+  "time_zone": "Australia/Sydney",
+  "country": "AU",
+  "currency": "AUD",
+  "tax_scheme": "GST",
+  "corrections": [
+    {
+      "schema": "bill/invoice",
+      "types": [
+        "credit-note",
+        "debit-note"
+      ]
+    }
+  ],
+  "categories": [
+    {
+      "code": "GST",
+      "name": {
+        "en": "GST"
+      },
+      "title": {
+        "en": "Goods and Services Tax"
+      },
+      "keys": [
+        {
+          "key": "standard",
+          "name": {
+            "en": "Standard"
+          }
+        },
+        {
+          "key": "zero",
+          "name": {
+            "en": "Zero"
+          }
+        },
+        {
+          "key": "exempt",
+          "name": {
+            "en": "Exempt"
+          },
+          "no_percent": true
+        },
+        {
+          "key": "outside-scope",
+          "name": {
+            "en": "Outside scope"
+          },
+          "no_percent": true
+        }
+      ],
+      "rates": [
+        {
+          "rate": "general",
+          "keys": [
+            "standard"
+          ],
+          "name": {
+            "en": "General rate"
+          },
+          "values": [
+            {
+              "since": "2000-07-01",
+              "percent": "10%"
+            }
+          ]
+        }
+      ],
+      "sources": [
+        {
+          "title": {
+            "en": "ATO - GST"
+          },
+          "url": "https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst"
+        }
+      ]
+    }
+  ]
+}

data/schemas/tax/regime-code.json

@@ -17,6 +17,10 @@
           "const": "AT",
           "title": "Austria"
         },
+        {
+          "const": "AU",
+          "title": "Australia"
+        },
         {
           "const": "BE",
           "title": "Belgium"

examples/au/invoice-au-au.yaml

@@ -0,0 +1,41 @@
+$schema: https://gobl.org/draft-0/bill/invoice
+$regime: AU
+uuid: 2d301f3b-370a-4e15-a554-a8e05f61e93b
+currency: AUD
+series: "2026"
+code: "AU0001"
+issue_date: "2026-04-03"
+
+supplier:
+  name: Example Supplier Pty Ltd
+  tax_id:
+    country: AU
+    code: "51824753556"
+  addresses:
+    - street: George Street
+      num: "100"
+      locality: Sydney
+      region: NSW
+      code: "2000"
+      country: AU
+
+customer:
+  name: Example Customer Pty Ltd
+  addresses:
+    - street: Collins Street
+      num: "200"
+      locality: Melbourne
+      region: VIC
+      code: "3000"
+      country: AU
+
+lines:
+  - quantity: "1"
+    item:
+      name: Software engineering services
+      price: "900.00"
+      unit: h
+    taxes:
+      - cat: GST
+        rate: general
+        key: standard

examples/au/out/invoice-au-au.json

@@ -0,0 +1,95 @@
+{
+	"$schema": "https://gobl.org/draft-0/envelope",
+	"head": {
+		"uuid": "8a51fd30-2a27-11ee-be56-0242ac120002",
+		"dig": {
+			"alg": "sha256",
+			"val": "9b83035fda7d9f82243097be6bfdfc321d431f25d4d355b2a00700ed5c9b6687"
+		}
+	},
+	"doc": {
+		"$schema": "https://gobl.org/draft-0/bill/invoice",
+		"$regime": "AU",
+		"uuid": "2d301f3b-370a-4e15-a554-a8e05f61e93b",
+		"type": "standard",
+		"series": "2026",
+		"code": "AU0001",
+		"issue_date": "2026-04-03",
+		"currency": "AUD",
+		"supplier": {
+			"name": "Example Supplier Pty Ltd",
+			"tax_id": {
+				"country": "AU",
+				"code": "51824753556"
+			},
+			"addresses": [
+				{
+					"num": "100",
+					"street": "George Street",
+					"locality": "Sydney",
+					"region": "NSW",
+					"code": "2000",
+					"country": "AU"
+				}
+			]
+		},
+		"customer": {
+			"name": "Example Customer Pty Ltd",
+			"addresses": [
+				{
+					"num": "200",
+					"street": "Collins Street",
+					"locality": "Melbourne",
+					"region": "VIC",
+					"code": "3000",
+					"country": "AU"
+				}
+			]
+		},
+		"lines": [
+			{
+				"i": 1,
+				"quantity": "1",
+				"item": {
+					"name": "Software engineering services",
+					"price": "900.00",
+					"unit": "h"
+				},
+				"sum": "900.00",
+				"taxes": [
+					{
+						"cat": "GST",
+						"key": "standard",
+						"rate": "general",
+						"percent": "10%"
+					}
+				],
+				"total": "900.00"
+			}
+		],
+		"totals": {
+			"sum": "900.00",
+			"total": "900.00",
+			"taxes": {
+				"categories": [
+					{
+						"code": "GST",
+						"rates": [
+							{
+								"key": "standard",
+								"base": "900.00",
+								"percent": "10%",
+								"amount": "90.00"
+							}
+						],
+						"amount": "90.00"
+					}
+				],
+				"sum": "90.00"
+			},
+			"tax": "90.00",
+			"total_with_tax": "990.00",
+			"payable": "990.00"
+		}
+	}
+}

regimes/au/README.md

@@ -0,0 +1,47 @@
+# Australia (`AU`)
+
+Australia uses a Goods and Services Tax (GST) system administered by the Australian Taxation Office (ATO). GOBL models the Australian regime with a 10% standard GST rate, support for GST-free and input-taxed supplies through the generic GST key model, ABN validation, and invoice validation rules for supplier and customer identification.
+
+## Public Documentation
+
+- [ATO - GST](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst)
+- [ATO - Tax invoices](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/tax-invoices)
+- [ABR - ABN format](https://abr.business.gov.au/Help/AbnFormat)
+- [Peppol PINT A-NZ BIS](https://docs.peppol.eu/poac/aunz/pint-aunz/bis/)
+
+## Tax Identity (ABN)
+
+Australian businesses are commonly identified by an Australian Business Number (ABN). The ABN is 11 digits long, usually written with spaces for display, but normalized in GOBL without separators.
+
+Validation follows the ABR checksum algorithm:
+
+| Position | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 |
+| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
+| Weight | 10 | 1 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 17 | 19 |
+
+1. Subtract 1 from the first digit.
+2. Multiply each digit by its weight.
+3. Sum the products.
+4. The total must be divisible by 89.
+
+## GST
+
+Australian GST distinguishes between taxable supplies, GST-free supplies, and input-taxed supplies. GOBL keeps Australia on the shared GST model and maps those concepts as follows:
+
+| Australian concept | GOBL key / handling | GST treatment |
+| --- | --- | --- |
+| Taxable supply | `standard` / `general` | 10% GST |
+| GST-free supply | `zero` | 0% GST through the shared GST zero key |
+| Input-taxed supply | `exempt` | No GST charged; used as the generic mapping for input-taxed treatment |
+| Outside scope / non-taxable | `outside-scope` | Not part of the GST calculation |
+
+| Rate Name | GOBL Rate Key | Percent | Since |
+| --- | --- | --- | --- |
+| General rate | `standard` / `general` | 10% | 2000-07-01 |
+
+## Tax Invoices
+
+- Suppliers must include their details and ABN.
+- Invoices of AUD 1,000 or more must identify the customer.
+- Self-billed invoices must identify the customer regardless of amount.
+- In this implementation pass, customer identification is satisfied by the customer's name; an AU ABN may also be included but is not required when the name is present.