The contract said 10%. The invoices said 300%.
A markup clause everyone had read, and nobody had reconciled against a single invoice line.
The contract set a ten per cent markup on supplied materials. It had been signed, filed and referenced in every subsequent conversation. What nobody had done was take the clause and lay it against the invoices being paid against it.
Line by line, back to source.
The contract, clause by clause, to establish what the client was entitled to be charged
The invoice lines behind the summary totals, rather than the totals themselves
The supplier's own source pricing where it could be obtained independently
The applied markup was not ten per cent. On the lines examined it ran to three hundred.
The overcharge was consistent rather than accidental, which changed how it had to be raised.
Nothing in the reporting the client received would ever have surfaced it. The summary was correct; the arithmetic beneath it was not.
The finding was documented with the clause and the invoice line attached to each item, so it could be raised as fact rather than as a suspicion. Rate reconciliation became a standing check rather than a one-off exercise.