Stress Testing a Client Debtor Book

Why stress test at all

A debtor book can look perfectly healthy right up until a key customer fails or the whole ledger slows at once. Stress testing is simply the discipline of asking, in advance, what such an event would do to the client's cash — before it happens, while there is still room to prepare. It turns an unexamined assumption that customers will keep paying into a tested one.

The exercise need not be elaborate. A handful of plausible adverse scenarios, run against the client's cash position, is enough to reveal whether the business is robust or quietly fragile. For an adviser, it is a structured way to move a client from optimism to preparedness without resorting to alarm.

Building the scenarios

Three scenarios cover most of the risk:

• The largest customer fails — remove their balance and future sales, and see what remains;
• The whole book slows — push average collection out by, say, thirty days;
• A cluster in one sector stalls — relevant where the client is exposed to a single industry.

Each is a what-if, not a forecast. The aim is to find the scenario that hurts most and understand why, so the client knows where their cashflow is genuinely vulnerable rather than worrying about every possibility equally. Keep the assumptions deliberately pessimistic but plausible — the test earns nothing if it quietly assumes the best. For a client heavily reliant on one customer the first scenario will usually be the painful one; for a client with a long, diverse book it is more often the across-the-board slowdown that exposes the thinnest cash buffer.

Reading the impact

Run each scenario through the client's cash forecast and watch the running balance. The questions are concrete: does the business still cover wages and the ATO through the period, how deep does any shortfall go, and how long until cash recovers? A scenario that breaches the overdraft limit or leaves payroll unfunded is the one that demands a plan.

Quantifying the impact is straightforward with the Merion calculator suite to model the cash effect of slower collection, layered onto the client's rolling cash forecast. The output is a clear view of how much shock the debtor book can absorb.

Acting on the findings

A stress test is only worthwhile if it changes something. Where it exposes dangerous dependence on one customer, the response is the diversification and monitoring covered under concentration risk; where it shows the whole book is too slow to withstand a wobble, the response is tighter collection and a cash buffer built in good times.

And where the test reveals balances already aged and at risk, recovering them now removes the exposure before a shock arrives. A client can refer an overdue commercial account without upfront cost at refer a debt. This is general information, not advice for a specific client.