How ProjectFi calculates your FIRE projections
ProjectFi uses real Australian financial rules and market-based assumptions to project your path to financial independence. Here's what's under the hood.
Tax Engine
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ATO FY2025-26 income tax brackets
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Medicare Levy (2%)
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Medicare Levy Surcharge
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Low Income Tax Offset (LITO)
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HECS/HELP repayment thresholds
Source: Australian Taxation Office
Superannuation
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Super Guarantee at 12%
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Concessional contributions cap: $30,000/year
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Non-concessional contributions cap: $120,000/year
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Division 293 tax (income >$250,000)
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Preservation age rules
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Unrestricted access from age 65
Source: Australian Taxation Office
Age Pension
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Assets test (homeowner vs non-homeowner thresholds)
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Income test with deeming rates
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Work Bonus ($300/fortnight)
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Taper rates applied per test
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Lower-of-two-tests rule applies
Source: Services Australia
Investment Returns & Inflation
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Default 7% nominal return (long-term Australian equity averages)
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Default 3% inflation (RBA target band)
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Both are user-configurable via dashboard sliders
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Real return = nominal return minus inflation
Monte Carlo Simulation
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1,000 independent trials per run
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Randomised annual returns using a normal distribution
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Historical Australian equity volatility
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Outcomes categorised: Early / On-Target / Late / Never
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Deterministic PRNG (mulberry32) for reproducibility
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Runs off the main thread via Web Worker
Drawdown Strategy
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Safe Withdrawal Rate (SWR) floor approach
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Default 4% SWR (based on the Trinity Study)
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Super drawn first after preservation age
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Non-super investments bridge the gap from retirement to super access
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Age Pension supplements income from age 67 (if eligible)
Strategy framework
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ProjectFi models the choices you make. The engine never picks a strategy on your behalf.
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Strategy choices live in three life-stage buckets: Accumulation (working years), Transition (FIRE to preservation age), and Drawdown (retirement).
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Each strategy field maps to a single decision the engine has to make, e.g. where surplus cashflow goes during accumulation, or which pot to draw from first during retirement.
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NEUTRAL defaults are explicitly labelled in the UI as "preview assumes [X] until you choose [field]". Once you pick, the engine honours every fully-live strategy. A small number of options are still "intent only" or "partially live"; the dashboard chips and the per-strategy guides flag those explicitly so you know what the chart is actually doing.
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Per-strategy guides explain what each choice does, when someone might apply it, and the honest trade-offs.
Source: Strategy guide
Important limitations
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ProjectFi is a projection tool, not a prediction. Actual outcomes will vary.
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Future tax rules, super caps, and pension thresholds may change
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For couple households, Medicare Levy Surcharge uses the ATO family thresholds but does not currently model the extra threshold uplift for the second and later dependent children
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Investment returns are not guaranteed and past performance does not predict future results
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The tool does not model all possible financial situations (e.g. Centrelink interactions beyond Age Pension)
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ProjectFi is a planning tool, not financial advice. Projections are estimates only. Please consult a licensed financial adviser before making investment decisions.
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