Field notes · 12 March 2026
Designing a sample that still finds weekend approvals
How we size claim samples for a financial audit of expense management applications without drowning AP in evidence requests.
A full population of expense claims is rarely testable line by line. The craft sits in the sample: enough weight on high-value travel, enough coverage of small-and-frequent items where policy gets quietly bent.
Start with how the application slices the world
Most expense management applications already tag claims by category, cost centre, and payment method. Use those tags before inventing new strata. If corporate card feed items and out-of-pocket reimbursements live in different queues, sample them separately — the failure modes differ.
Put calendar pressure in the design
Weekend submissions, month-end rushes, and the week after a sales conference produce different behaviour. We often oversample the last five business days of each month because approval shortcuts cluster there.
Leave room for follow-up items
When a sampled claim lacks a receipt, the next request should be specific: claim ID, date, and what evidence would close the point. Vague follow-ups train AP teams to ignore auditors.
What “enough” looks like
There is no universal percentage. For a mid-size Thai entity with a few thousand claims a year, we frequently land between 40 and 90 tested items for a full application audit, adjusted when exception rates climb. The management letter should say why the size was chosen — committees notice when the number appears out of thin air.