March APIsExplore the API

Australian data infrastructure

Verified rules.
Useful APIs.

March APIs turns complex public rules into dependable product infrastructure. Source-backed, deterministic and ready to integrate.

Start free on RapidAPI See our first API
GovCost AULive

Estimated government charges

$32,802.46

Transfer duty$32,437.00
Registration fees$365.46
Rulensw-2026-07-01Verified twice
100%Integer cents
0Inferred facts

Built for teams that cannot afford an unexplained number.

Official source linksCalculation tracesVersioned rulesExplicit limitations

Product 01

Government charges,
ready for your product.

GovCost AU

Property government cost API

Calculate supported Australian government charges without maintaining rate tables inside your application. NSW property transfer duty and registration fees are available now.

  • One request for duty and selected registration fees
  • Rule versions, assumptions and official sources returned
  • Clear typed errors for unsupported scenarios
  • Free launch tier available through RapidAPI
View GovCost AU
POST /v1/property/estimate200 OK

Request

{
  "jurisdiction": "NSW",
  "contract_date": "2026-08-15",
  "dutiable_value_cents": 85000000,
  "transaction": {
    "property_type": "residential_home",
    "whole_property_acquired": true,
    "arm_length_transaction": true
  }
}

Response

{
  "duty_cents": 3243700,
  "transfer_registration_cents": 18273,
  "mortgage_registration_cents": 18273,
  "total_cents": 3280246,
  "rule_version": "nsw-2026-07-01"
}

How we build

Evidence is part
of the output.

01

Source-backed

Every production rule points to authoritative evidence and must pass two documented verification checks.

02

Deterministic

Identical supported inputs return identical integer-cent outputs, without model inference or hidden rounding.

03

Fail-closed

Unsupported or legally ambiguous scenarios return an explicit error instead of a plausible-looking guess.

Designed to slot into

Mortgage platformsProperty applicationsConveyancing softwareAccounting products

Coverage

Start narrow.
Expand with evidence.

Available now
NSW property costs

Standard residential purchases by supported individual purchasers, including transfer and mortgage registration fees.

Expansion model
More jurisdictions and public-rule APIs

New coverage ships only after sources, boundaries, calculation behaviour and reproducible verification are documented.

Build with confidence

Put a traceable number
in your product.

Start with GovCost AU