About // PaymentCalcs
About PaymentCalcs
PaymentCalcs is an independent Australian project that builds deterministic financial calculators: pay, tax, mortgage, property, loan, savings and small-business arithmetic. Every result renders its full working (formulas, intermediate values, assumptions, sources and limitations) beside the number.
How the numbers are produced
No statutory value is written from memory. Every rate, threshold and bracket lives in a versioned rule pack that records the official document it came from (source URL, publishing authority, retrieval date and a content hash of the retrieved document), so any figure on the site can be traced back to its source.
Calculation engines are pure functions of the request and the rule packs. They perform no network access and read no clock, so the same inputs against the same pack versions always produce the same result. Money is held in integer cents; rate arithmetic uses decimal maths, never floating point.
If a verified rule pack cannot be resolved for the selected jurisdiction and date, the calculator says so and stops. It never substitutes another year's rules, another state's rates, or a plausible number. No large language model takes part in any calculation path.
What the results are
Results are general information calculated from your inputs and published rules. They are not financial advice, not a quote, and not a substitute for the official calculators run by the ATO or state revenue offices. Concession and eligibility decisions rest with the relevant authority, not with this site.
Who runs it
PaymentCalcs is built and operated independently in Australia. The full source code, rule packs and change history are public on GitHub, so the working behind the working is inspectable too.