Methodology

How the calculators work, and the difference between official rules and the assumptions you choose.

Official rules vs your assumptions

Rates and thresholds set by law (e.g. stamp-duty tiers, CPF contribution rates, retirement sums) are treated as official rules and linked to their source. Returns, inflation, lifespan and future costs are your assumptions — change them to see different outcomes.

Effective dates

Where a rule is date-dependent (e.g. Seller's Stamp Duty by acquisition date, CPF schedules by year), the calculator selects the schedule that applies and the page states the effective date.

Projections and rounding

Figures beyond officially confirmed periods (e.g. long-run CPF interest, future retirement sums) are projection assumptions and labelled as such. Tax and duty outputs follow the official rounding where defined.

How rules are reviewed

Figures are checked against the primary official sources and dated. Rules change; always confirm against the cited source before acting. Current check: 21 June 2026.

Limitations

The models simplify real life. Bank credit assessments, underwriting, individual reliefs and edge cases may differ from the estimate. Results may not match an official or institutional assessment.