Move approved usage measures into billing with versioned extracts, contract rules, and exception ownership. The working definition should name the covered entities, accounts, period, source systems, cutoff, preparer, reviewer, and the event that closes a row. A queue is useful only when another person can tell what is ready, what is waiting, and what decision remains protected.
For this workflow, record customer, contract ID, meter, usage period, source version, quantity, unit rate, adjustment, approval, invoice line, owner, and evidence link. Use stable identifiers from the governing systems. Free-text notes may explain an exception, but they should not replace the transaction ID, source date, amount, status, or evidence location that lets the reviewer reproduce the result.