Work out interim payment certificate instantly with clear inputs, formula shown and shareable results.
An interim certificate values the work cumulatively, adds materials properly stored on site, deducts retention, then subtracts everything previously certified. Working cumulatively rather than period by period is what allows earlier valuations to be corrected without a separate adjustment.
Certificate
Net due = (work executed + materials on site) x (1 - retention rate) - previously certified
Net due = (work executed + materials on site) x (1 - retention rate) - previously certified. An interim certificate values the work cumulatively, adds materials properly stored on site, deducts retention, then subtracts everything previously certified.
The contractor has paid for them but has not yet earned the installed value. Including them at cost improves cash flow without paying for work not done, provided title and insurance are in order.
This calculator takes 4 inputs: Value of work executed, Materials on site, Retention rate, Previously certified. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.