NovDeal stress test: the conditions under which a purchase stops making sense
Every pre-purchase calculation rests on assumptions, and they are almost always the optimistic ones — otherwise you would not have reached the calculation. A stress test does not argue with the base case. It takes your own numbers and worsens them one at a time until the deal stops holding. The point is not to frighten yourself but to learn the line in advance: where exactly your particular deal breaks and what you will do at that moment. This is precisely the check that cannot be performed in hindsight.
What breaks first
Contrary to expectation, it is usually not price that breaks but time. The first tenant takes longer to find, handover arrives later, the sale at exit drags on. Every extra month is a month of costs with no income; it hits your buffer while the value of the property has not moved anywhere. That is why a stress test starts with timing and only then moves to yield.
Ordered by how soon they tend to arrive, the factors run roughly like this: timing first, then actual rent and running costs, then price and currency at exit — and running alongside all of it, your own need for cash.
Seven factors and the margin of safety for each
| What goes wrong | How to measure the margin | What it tells you |
|---|---|---|
| Vacancy longer than expected | How many months without rental income you can cover from reserve without disturbing ordinary life | If the margin is shorter than the time it realistically takes you to find a tenant, the property is not ready to be let without an extra buffer |
| Rent below plan | How far rent can fall before it stops covering service charges, management, taxes and repairs | Calculated on the break-even page; a narrow margin means the income depends on a perfect scenario |
| Delayed handover | How many months of delay you withstand on payments and on personal plans; separately, what the contract says about it | If the delay breaks your payment schedule, the question moves from financial to contractual |
| Rising running costs | How far service charges, utilities, insurance and repairs can rise before net flow turns negative | Costs rarely fall; a minimal margin means the plan depends on things you do not control staying unchanged |
| A lower exit price | How far below expectation the sale price can be while you still exit without a loss after transaction costs | Measure from your effective net price, not from the list price |
| Currency | The gap between the currency you spend in and the currency of income and proceeds: how the result looks if the gap moves against you | Currency difference is your risk, not a technicality; it belongs in the mandate |
| Your own need for cash | What you do if the money is needed before your horizon: a rushed sale, a pledge, a loan | This is the most common real exit scenario and the most expensive one, because the deadline decides, not the price |
How to run the test
- List your base assumptions: handover date, rent, months of vacancy, running costs, sale timing and price, currency. One line each.
- Mark the source next to each: confirmed by a document, said verbally, assumed by you. Verbal and assumed are the first candidates for worsening.
- Worsen one factor at a time and look at the result. Worsening everything at once is pointless: you get a scenario no deal survives, and it teaches nothing.
- Find the breaking point: the value at which you have to touch the reserve or sell earlier than planned.
- Compare that point with your investment mandate. Whether a stop condition is breached is the answer the test gives.
- Write down what you will do if the scenario arrives. A plan made in advance is worth more than a precise number.
An illustrative example: measuring the vacancy margin
The numbers below are invented for the arithmetic. They are not Phnom Penh market figures and not a benchmark for rent, yield or vacancy — substitute your own.
Suppose your monthly costs on the property are 100 notional units: service charges, a utilities minimum, upkeep. You plan on rent of 200 notional units. The reserve you are willing to spend on this property without disturbing your life is 600 notional units.
In a month with no tenant you lose 100 units of costs and 200 units of income you did not receive, but what leaves your pocket is the 100. The reserve covers six months of complete vacancy — that is your margin in time. If, in your own scenario, finding a tenant realistically takes far less than six months, you have a margin. If your own expected search time is close to six months, you have none: you are planning the deal right at the line.
The same method applies to the other factors. Change one parameter, see after how many months or at what price level you run into the reserve, and compare that with what you wrote in the mandate.
The reserve is the one universal answer
Each factor has its own mechanics, but all of them are absorbed the same way: with money that takes no part in the deal. A reserve is not "whatever is left after the purchase" — it is a sum you have forbidden yourself to touch for this property.
The practical rules are simple. Hold the reserve in the currency of your expenses, not the currency of the property. Keep it out of the purchase budget, however tempting a larger unit is. And count it in months rather than percentages: months are clearer, because nearly every bad scenario is measured in time.
There is one sign that the reserve is too small: to hold the deal together in a moderately bad scenario you have to spend the money you declared untouchable, or sell within a timeframe you declared unacceptable.
Three outcomes of the test
- Continue checking. The deal withstands worse assumptions, no stop condition in the mandate is breached, and the usual open questions on documents and contract remain.
- Negotiate the terms. The deal works, but only on different parameters: another price, another payment schedule, a bigger reserve, a different unit in the same project. The conversation then becomes about terms rather than about "buy or not".
- Walk away. What you found is compensated by neither price nor income. A separate verdict is "more data needed": if the calculation collapses when one unconfirmed assumption changes, confirm the assumption before recalculating.
To be explicit: a stress test does not make a deal safe and does not predict the future. It only shows which of your assumptions carries the whole structure. Usually there are one or two such assumptions, and it is useful to know them before signing rather than after.
What to calculate alongside
The stress test relies on numbers that are worked out on other pages and does not repeat them:
- Return metrics — what exactly you are worsening, and how gross differs from net.
- Rental break-even — the level below which rent stops covering costs.
- Purchase costs and effective net price — the base from which any exit is measured.
- Investment risks and the purchase risk register — what can go wrong and how to record it for your own deal.
- Investment mandate — the limits against which you read the test result.
Want to test your assumptions for robustness? We will go through your calculation factor by factor and show which assumption is carrying the whole structure. No yield promises and no deadline pressure.
Review my calculationTelegramFrequently asked questions
What is a property deal stress test?
It is a check of your own calculation against a bad scenario before you sign. You take your own assumptions — rent, occupancy, handover date, running costs, exit price — and worsen them one at a time, then see at what point the deal stops holding. The aim is not to arrive at an optimistic number but to know in advance the line beyond which the decision has to change.
What breaks first in the calculation?
Usually time, not price. The first tenant takes longer to find, handover comes later, the sale at exit drags on. Every extra month is a month of costs with no income, and that is what eats the buffer while the value of the property has not moved at all. So it is sensible to start a stress test with timing rather than with yield.
How do I know the margin of safety is too thin?
There is one sign: to hold the deal together in a bad scenario you have to touch money you declared to be your reserve, or sell within a timeframe you declared unacceptable. If even one moderately bad scenario leads to a forced sale, the margin is too thin — however attractive the base case looks.
What conclusions besides walking away can a stress test give?
Three outcomes, not two. First: the deal withstands worse assumptions and you continue with the usual open questions on documents. Second: the deal works only on different terms — another price, another payment schedule, a bigger reserve — so the conversation becomes about terms. Third: neither price nor income compensates for what you found, which is a refusal. There is also a separate verdict of "more data needed": if the calculation collapses when one unconfirmed assumption changes, confirm that assumption first.
Sources
NovAsia editorial corpus on preparing an investment decision · practice supporting buyers in Phnom Penh · checked July 2026. There are no market figures on this page: rental rates, yields, vacancy levels and price growth are not given, and the numbers in the illustrative example are invented to show the arithmetic. This content is for general information only, is not individual investment, legal or tax advice, and contains no promise of any outcome.