Learn · Component 2 — Tools and calculators (`/tools/)
liability estimator
Estimate programme liability by connecting issued value to point value, redemption behaviour, reversals, expiry, and reward fulfilment cost.
## The mechanism
The rule needs a clear trigger, a measurable balance change, an owner, and a correction path. Keep member promise, ledger event, liability, and fulfilment cost as separate concepts.
## Worked example
A member earning 2 points per dollar on 400 dollars of spend holds 800 points. At a 1 cent point value, that balance represents 8 dollars of liability. Use these quantities to test the page rule, cost, or control.
## Do it
Write the trigger, input, owner, exception path, and reconciliation check. Test a normal event, a reversal, a redemption, and a member-facing explanation before relying on the result.
## Common mistakes
- Hiding a material assumption. Put the unit and trigger beside the result. - Ignoring reversals. Test the correction path. - Using a blended total. Split value, cost, funding, and operating ownership. - Treating a promise as a ledger event. Name the event that creates value.