How to stress-test cash flow for a late customer payment

A late payment changes the dates on your forecast. It does not automatically reduce revenue or make the whole invoice a loss. Test the delay first, then consider a separate non-payment scenario if there is evidence for it.

Start with receipts, not invoice dates

This four-week example opens with 5,000. Forecast receipts are 2,000, 1,000, 6,000 and 2,000. Payments are 3,000, 4,500, 2,000 and 2,500. All figures refer to cash movements and use one consistent tax convention.

Week	Base receipts	Payments	Base closing cash	Delayed closing cash
1	2,000	3,000	4,000	4,000
2	1,000	4,500	500	−500
3	6,000	2,000	4,500	3,500
4	2,000	2,500	4,000	4,000

The delayed column moves the week-2 receipt of 1,000 to week 4. Week 4 therefore receives 3,000, and the end balance is unchanged. The business nevertheless runs 500 short in week 2. Looking only at month-end cash conceals that problem.

Add a stated minimum balance

If the owner chooses a planning floor of 1,000, the base case already needs 500 more cash at its low point. The delayed case needs 1,500. This floor is an assumption, not a universal reserve recommendation.

Weekly buckets can also hide a Monday payment before a Friday receipt. Where headroom is narrow, use dated daily entries and sort them by expected clearance. Do not offset future receipts against money due today.

Choose an action that actually changes timing

For this scenario, collecting 1,500 earlier or moving an agreed 1,500 outflow beyond the low point restores the selected floor. A 500 transfer only eliminates the negative balance. Confirm the action before putting it in the base forecast; until then it is an alternative scenario.

Avoid counting both an invoice and its payment as separate receipts. A credit facility is also not an ordinary sale: record its draw and subsequent repayment separately, including costs, and do not treat unapproved credit as available cash.

Reconcile against what happened

At the end of each week, replace estimates with cleared receipts and payments. Carry the actual closing balance into the next week and extend the horizon. Track the reason for changes: invoice approval, dispute, expected transfer or uncertain collection. The cash forecast guide explains the starting structure; profit versus cash flow explains why a profitable month can still contain this gap.

If the receipt never arrives, remove it rather than postponing it indefinitely. In that separate scenario, week-4 cash ends at 3,000, not 4,000. Any accounting treatment of doubtful debt is a separate question from this timing exercise.

Method and scope

All amounts above are hypothetical teaching figures in one currency, excluding tax unless stated otherwise. These are original scenarios, not market prices, benchmark targets or professional recommendations. The references support the underlying concepts, not the example assumptions. This AI-assisted explanation has not had independent professional review. Calculation methods and limitations.