Methodology & sources

The dataset

The current dataset is an indicative snapshot of 29 NSW suburbs (as of 2026-06-01), modelled on public-data patterns. It exists so the product’s engines, scoring and UX can be exercised end-to-end; the roadmap’s Phase 1 replaces it with scheduled ingestion of the sources below. Treat suburb figures as illustrative until then — the calculator mathematics (tax, duty, serviceability) is real today.

Every formula, in plain language

Net income

FY2025-26 resident tax brackets (0% to $18,200 · 16% to $45,000 · 30% to $135,000 · 37% to $190,000 · 45% above) plus 2% Medicare levy, applied per applicant.

Assessed expenses

The higher of your declared monthly expenses or a HEM-style benchmark floor (single $2,250/m, couple $4,100/m, +$500 per dependant), plus debt repayments, credit card limits × 3.8%/month, and an income-contingent HECS estimate.

Borrowing capacity

Maximum loan = the 30-year P&I loan whose repayment at the assessment rate (advertised variable 5.49%/5.84% + 3.0% APRA buffer, floor 5.5%) equals your monthly surplus. Buying power then subtracts NSW transfer duty, ~$2,500 legals and any LMI from loan + deposit, solved iteratively because duty depends on price.

NSW transfer duty

Indicative FY25-26 brackets from 1.25% to 7% (premium). First-home buyers: full exemption to $800k, linear concession phase-out to $1m.

LMI estimate

Indicative premium bands by LVR: ≤80% none · 80–85% ~1.0% of loan · 85–90% ~1.8% · 90%+ ~3.0%.

Stress test

Repayments recomputed at advertised rate +0/+1/+2/+3 percentage points; a result is flagged “stressed” when repayments exceed 30% of net income.

Net worth

Your net worth is the sum of every holding’s current value, across all asset classes — property, equities, crypto, ETFs, term deposits, superannuation and cash all flow through the same deterministic roll-up. Each holding also reports its cost basis, unrealised gain (current value − cost basis) and its share of the total, so the headline is fully explainable.

Holding valuation

A market holding (equities/crypto) is valued at quantity × its latest price-feed snapshot, marked to the free Yahoo Finance / CoinGecko feeds; a manual holding (cash, ETF, super…) carries an explicit current value you enter. Cost basis = quantity × unit cost + any entry costs. A holding with no valuation is counted as $0 and flagged.

Net worth over time

The trend chart takes the union of every holding’s valuation dates and, at each date, sums each holding’s value as at that date — a position counts as $0 before its first valuation, so the curve grows naturally as holdings are added rather than jumping.

Allocation & concentration

Allocation is each asset class’s share of net worth. The engine raises plain-language cautions when a single class dominates the portfolio, and when illiquid assets (property, term deposits, super) are concentrated — signals to consider, never automated advice.

Suburb score

Affordability is a HARD GATE (median ≤ buying power), never a weight — failing suburbs are excluded outright, never down-weighted, and affordability can never be traded off against anything else. Passing suburbs score 0–100 from weighted quality components: growth drivers (5-yr CAGR, population, infrastructure, supply balance), yield & rental cover, lifestyle & access, risk (inverse of flags, vacancy, oversupply, investor concentration), and the market-sentiment index. Weights are user-adjustable and normalised; presets differ for investors vs owner-occupiers.

Sentiment index

Explainable composite 0–100, each signal carrying a plain-language reason: auction clearance (28%), days-on-market trend (20%), rental vacancy (20%), search interest (20%), news sentiment (12%). Lower vacancy and falling days-on-market read as firmer demand. All signals are shown on each suburb page, ordered by their contribution.

AI advisor guardrail

The language model receives calculator outputs as context and may only repeat numbers that appear there. It computes nothing. With no API key the advisor returns a deterministic narration of the same outputs.

Privacy & compliance posture

• Your financial profile is stored in your browser (localStorage) only. Calculator API calls are stateless — nothing is persisted server-side. No analytics on financial inputs. No data is ever sold.
• PropertyPath provides general information and educational tools — not personal financial product advice (ASIC), and not credit assistance (NCCP). It never recommends a specific property, loan or lender.
• All monetary outputs come from deterministic, version-controlled code. The AI layer narrates; it cannot compute or invent figures.
• Indicative data is labelled as such wherever it appears, with its snapshot date.
• We track application errors and performance through privacy-respecting monitoring to keep the service reliable. Your financial inputs are never sent to error tracking or any analytics — only anonymous technical telemetry (error stack traces, page timings) leaves the browser, and only in production.