Methodology - Smart Money Calculator

How calculations are built

Each calculator models a defined scenario from stated inputs, assumptions, and applicable rules. The aim is to make the logic inspectable and useful for planning, while avoiding a claim that one result fits every person or situation.

Source hierarchy

Sources are prioritised in this order: legislation and government or HMRC publications; regulators and public guidance bodies; original research; then reputable secondary explanation. Secondary sources can help explain a topic but do not replace a more authoritative source when one is available.

Rounding and displayed results

Displayed currency may be rounded for readability while internal calculations keep precision. Rounding can mean a displayed total differs slightly from the sum of displayed components.

Review cadence and tax-year updates

Tax-year pages show their applicable year and review date. Calculations are reviewed when relevant rules change; this is a review policy, not a promise of a particular update frequency.

Testing and validation

Calculation logic is tested separately from UI rendering. Tests cover representative inputs and expected results, while the interface is checked to ensure those calculations are presented and interacted with correctly.

Corrections

To report a possible error or suggest an improvement, use the public GitHub profile. Reports are reviewed when rules change or an issue is identified; no response time is promised.

Advertising independence

Advertising does not determine calculator formulas or results. Advertising and any third-party links are kept separate from the calculation logic.

Limits of the tools

These tools provide scenario modelling rather than financial, tax, legal, mortgage, pension, or investment advice. Check important assumptions, rates, thresholds, and rules before relying on a result, and seek professional advice where appropriate.