Methodology
Every number QuoteClear shows is reproducible from this page and your inputs. The engine is deterministic, unit-tested (54 tests including hand-derived golden quotes), and versioned. If you find an error, that's a bug — tell us.
Effective finance rate
We solve the internal rate of return on the lease's cash flows: amountFinanced = Σ repayment/(1+r)^t + residual/(1+r)^n (payments in arrears), annualised as (1+r)^ppy − 1. Because the financed amount contains every financed fee and add-on, this effective rate exposes gaps between a quoted 'base rate' and what you actually pay. Solved by Newton–Raphson with bisection fallback; target accuracy ±0.05 percentage points.
Tax engine (versioned by financial year)
Resident income tax brackets with LITO, Medicare levy (2% with low-income shade-in), and the marginal HELP repayment system in force from 2025-26 (threshold $67,000; 2026-27: $69,528). All rates live in versioned reference data — never hard-coded — and are re-verified against ATO publications each year. Current configs: 2025-26, 2026-27 (verified 2026-10-09).
FBT & the RFBA cascade
Car fringe benefit valued by the statutory formula method (20% of base value). Employee contributions (ECM) reduce the taxable value dollar-for-dollar. FBT-exempt EVs (eligible ZEVs first held from 1 Jul 2022, under the LCT fuel-efficient threshold — $91,387 in 2025-26, $91,661 in 2026-27) pay no FBT, but the notional taxable value is a REPORTABLE fringe benefit, grossed up at type 2 (1.8868) when above $2,000. The RFBA flows into HELP repayment income — the cascade most quotes omit. FBT rate 47%, type 1 gross-up 2.0802.
Residual check
Quoted residuals are compared against ATO minimum guidelines for 8-year-effective-life vehicles (1yr 65.63%, 2yr 56.25%, 3yr 46.88%, 4yr 37.50%, 5yr 28.13%). A residual below the guideline is flagged as a red flag; above it increases the end-of-lease obligation.
True total cost
Lease repayments + admin fees + running costs + optional products + residual − tax benefit − GST benefit. The GST benefit is approximated as input tax credits up to the car depreciation limit ($69,674 in 2025-26) passed through to the financed amount (price/11). We never present the payroll deduction alone as 'cost'.
Deal score (published rubric)
Vehicle price /20 (financed amount vs vehicle price), Finance /25 (effective-rate bands: ≤7.5% sharp, 7.5–9% competitive, 9–11% above market, 11–13% high, >13% very high), Provider fees /15 (term-total bands), Running costs /15 (bundled insurance vs your comparison quote), Optional products /15 (none is best), Transparency /10 (rate disclosed, fees itemised, residual compliant). Every point is deterministic — no AI judgement.
EV FBT phase rules
Reference data tracks: the 2022 Electric Car Discount; the PHEV exemption end for new arrangements from 1 Apr 2025; and the May 2026 announcement (NOT yet legislated) of BEV wind-back phases from Apr 2027 and Apr 2029, with grandfathering for existing leases. Outputs label announced-vs-legislated settings.
What we don't do
No AI performs any financial calculation. We don't recommend products or providers, don't rank by commercial relationships (there are none), and don't present personalised tax outputs as advice — all tax figures are illustrative estimates from published ATO settings and your inputs.