AIM-HR: An Open Model for Australian Housing Reform

Australia's housing debate is informed by a small number of proprietary models. The assumptions in those models are not publicly auditable. Reform proposals are routinely killed or carried by selective citations of those closed analyses. AIM-HR exists to make the mechanics of housing reform legible to anyone with a browser and the patience to follow assumption-by-assumption logic.

Supply module: planning-system throughput, construction cost curves and developer behaviour. Demand module: demographic flows, formation and dissolution of households, income distribution. Tenure module: ownership/rental transitions and policy levers across each. Tax module: stamp duty, land tax, negative gearing, capital gains.

Each module is independently testable. Outputs are reproducible from declared parameter files. Source data is cited at the parameter level so users can substitute their own evidence and re-run.

Baseline: current policy settings projected forward. Supply-only: significant planning-system reform without tax changes. Demand-only: significant tax reform without supply response. Combined-reform: both. Property-tax-shift: stamp-duty-to-land-tax transition under several glide paths.

The combined and tax-shift scenarios outperform the baseline on every credible affordability indicator across the parameter ranges tested. The supply-only scenario underperforms expectations when treated as a standalone lever.

This is a methodology and reference report, not a prescriptive recommendation. It is published for consideration by researchers, councils, advocates, parliamentarians and the public. Use the model. Disagree with the assumptions. Substitute your own. Publish what you find.