Compare budget choices, understand the trade-offs and save your experiment. Return to your original explorer tab to keep the settings you are working on.
Start with a question
Use this explorer to ask questions such as: “What if the Commonwealth collected more income tax and spent the same extra amount on health?” It shows the direct budget trade-off each year. It does not predict the effects on jobs, growth, wellbeing or services.
- Open Projections. Read the income, spending and budget gap for every $100 of the economy, then compare the outcomes on the four pathway cards.
- Choose a pathway to load its settings, or keep BAU.
- Move a slider or type a number. Press Enter or leave the field to apply a typed value.
- Inspect a year. Read the resulting deficit or surplus, the change from BAU and the effect on states. Choose a different chart measure or hide comparison lines without changing your settings.
- Use Undo to go back. Reset returns to BAU; it can also be undone.
What the sliders mean
Each setting is an annual change in percentage points of GDP. GDP is a measure of the size of the economy. A setting of +0.10 means extra receipts or spending equal to one-tenth of 1% of GDP each year at full effect. It is not a 0.10% change in a tax rate or in the size of a department.
A positive revenue number means more money collected. A positive spending number means more money spent. Negative numbers mean less. Zero keeps the reference amount.
Try personal income tax at +0.10 and health at +0.10. At full effect they offset each other, so the direct balance change is zero. This says nothing about who pays the tax or who benefits from the health spending.
Open When should your changes happen? to choose the start year and how many years they take to reach full effect. With a five-year phase-in, the first year applies one-fifth, the second two-fifths, and so on. The full annual share continues thereafter. Late changes may not reach full effect by 2050–51.
The control limits are exploration ranges, not estimates of what a policy could deliver. Invalid numbers leave the last valid setting in place.
What the four pathways contain
BAU uses the 2026 Intergenerational Report (IGR) reference. It is an official long-run projection under assumptions, not a promise about the future.
The three “improvement” pathways are illustrative allocations created for this explorer. They are not party policies or forecasts. Each step collects an extra 0.15 percentage points of GDP in personal income tax and 0.05 in other income taxes. It spends 0.04 on education, 0.03 on infrastructure and 0.03 on health. That leaves 0.10 more direct fiscal room at full effect.
- minor improvement: one step.
- significant improvements: two steps.
- transformation improvements: three steps.
All other controls, including NDIS, start at zero. These fixed comparison paths begin in 2027–28 and phase in over five years. Your edits and timing change only your experiment. Loading another pathway replaces your settings; Undo restores the previous experiment.
The names come from the simulation family pattern. They do not prove better productivity, fairer outcomes or better services. At full effect, these illustrative packages go above the IGR’s assumed 24.2% tax-to-GDP ceiling. Higher receipts have costs for taxpayers; extra spending may or may not achieve its aims.
GST and NDIS: who pays?
GST: all extra GST receipts are passed to states and territories. That increases both Commonwealth receipts and payments by the same amount. The direct Commonwealth balance change is zero. Any income-tax cuts or household compensation you add still need funding.
NDIS: the slider changes assumed participant cash payments. The explorer shows two alternatives for that change:
- Commonwealth pays all of it.
- States pay an assumed 26% and Commonwealth pays 74%.
For an extra 0.50 percentage points of GDP at full effect, the Commonwealth balance change is −0.50 in the first case and −0.37 in the second. In the second case states contribute 0.13. A cut in payments also reduces state contributions under that assumption.
The 26% is illustrative. NDIA Portfolio Budget Statements Table 2.1.1 shows about 26.3% state funding in the 2027–28 to 2029–30 forward estimates, versus 24.6% in the 2026–27 budget year. These are expense-basis contribution proportions, not a cash funding rule. It is not a constant established by official rules for the next 25 years. Actual agreements, caps, reconciliations and cash/in-kind differences are not reproduced. These are alternatives, not statistically estimated bounds. Neither case predicts what happens to participants.
Use the research without double counting
Government & policy lets you choose a government period, inspect an annual budget outcome and examine the largest balance movements. Transition years appear in both relevant filters, but are never added into party totals. Income and spending changes explain the arithmetic; they do not measure a policy’s causal effect. Sourced milestones cover the financial crisis, NDIS trials, pandemic support and the 2024 income-tax changes.
The reference section separates announcements, official projections and historical outcomes. “Explore” takes you to a relevant control without applying a policy. Check whether an announced change is already included in the reference before adding another amount.
Productivity reforms groups the research into seven themes, beginning with the Productivity Commission and including several think-tank perspectives. Choose a theme to see its possible mechanism, evidence, trade-offs and controls together. Changing themes does not apply a policy or erase your experiment.
The sliders in these themes are the same settings used in Projections. Changing health in the research tab changes health in the main charts once. It does not add a second health policy. Do not count one capital project as both education and infrastructure, or count one receipt change under two taxes.
Published research results may use different years, governments or definitions. For example, Grattan’s tax package is a one-year example with different state-transfer arrangements. It is not loaded as a 25-year preset. Prevention benefits are not assumed to be annual Commonwealth savings.
Explore history and public preferences
History follows Projections. It starts in 2000–01, the financial year ending in 2001. The aggregate chart uses the 2025–26 Final Budget Outcome, released on 28 September 2026. Category context uses IGR chart data, with gaps shown explicitly. Its 2025–26 values precede the final outcome and can be estimates.
Move the historical year slider to see actual income, spending and balance. Choose dollars or a share of the economy for the aggregate charts. Dollar values are nominal, not inflation-adjusted. The category cards show the selected year’s published context. Select one for its chart, definitions and a link back to the relevant projection control. Downloads preserve missing observations.
All 15 controls have an entry. Some categories start later, pensions have only a 2025–26 value in the selected IGR series, and no compatible other-spending history has been established. Missing values are not zero.
Total NDIS includes both levels of government. Defence uses NATO expenditure definitions. The infrastructure series covers only the Infrastructure Investment Program. Non-tax history includes items excluded from the editable control. Do not add these different category series into a cash budget.
From 2005–06 through 2019–20, published underlying cash balance also subtracts net Future Fund earnings. The explorer preserves that published figure rather than forcing it to equal receipts minus payments.
Public Sentiment now shows the two published AES chart series on lower taxes and more social-service spending for nine election years from 2001 to 2025. These values were transcribed and visually checked against printed page 121 of the AES trends report. They are not a new analysis of survey microdata. Use the survey-year slider and download the published observations.
The two series do not cover every response or sum to 100%. Exact grouping rules and question-level denominators remain unverified, so no missing response category, confidence interval or statistical significance has been calculated. Whole-survey sample sizes are clearly labelled as such. Collection methods changed; lines only join observations. The tab links to methods and opens the relevant tax-and-services controls without applying settings.
Keep and share your experiment
Save scenario downloads a small JSON file with your 15 settings, pathway, timing, NDIS funding case, model version and dataset identity. Load restores those settings. A file from a different model or dataset is rejected without changing your current experiment.
Open Annual results & calculation details to see the yearly figures and each contribution. Download annual results CSV saves all 25 years with the settings, timing weight and units. The combined direct change adds Commonwealth and state effects, cancelling transfers between them. These are annual ratios and changes, not cumulative dollar totals.
The guide opens in a separate tab. Return to your original explorer tab to keep the current experiment. Save before closing or refreshing that tab; the explorer does not automatically keep settings after a reload.
What the result can and cannot say
The main result is the direct annual balance change before additional interest. Extra receipts improve that balance; extra payments reduce it. Linked state transfers are included once.
The chart showing reference plus direct changes keeps the official IGR reference and its published rounding differences. It is an illustration, not a new official forecast. Existing reference interest is included in the reference; additional interest, debt and GDP responses are not calculated. No future dollar amounts are manufactured from an unverified GDP path.
Household distribution, behavioural responses, service quality, productivity, jobs and implementation feasibility are not measured. A lower spending number is not evidence of efficiency. Use the research and your own judgement alongside the budget arithmetic.
Sources: 2026 IGR; 2025–26 Final Budget Outcome Appendix B. Further primary links appear beside the research in the explorer. Use these illustrations to explore assumptions, not as official forecasts or costed policy proposals.