Am I one bad month away from trouble?
Not a dramatic collapse. Just one month where revenue dips, an unexpected bill lands, or a big customer pays late. Could that single bad month push you into a cash crisis? Here is how to find out.
The short answer
Are you one bad month from trouble? Take your current cash and subtract one month of expenses plus a realistic bad-month scenario (lost revenue, late payments, or an unexpected cost). If the result is negative or barely positive, you have almost no margin of safety.
How one month can break a profitable business
Your business is profitable on paper. Revenue is steady. Bills are getting paid. Then three things happen in the same month: your biggest client delays their payment by 30 days, your annual insurance premium comes due, and a piece of equipment breaks.
None of these are catastrophic on their own. Together, they create a $25,000 cash gap that your $18,000 bank balance cannot cover. You miss a vendor payment, which delays a project, which delays the next invoice. The cascade starts from one bad month.
The question is not whether bad months happen. They always do. The question is whether your business has enough padding to absorb one without triggering a crisis.
The bad-month stress test explained
This test combines your cash position with a realistic downside scenario. Here is how to think about it:
The key variable is what counts as “bad.” For most small businesses, a bad month means revenue drops 30-40%, a large payment is delayed, and one unplanned expense shows up. If that combination leaves you unable to make payroll or pay rent, you are one bad month away from trouble.
How to run a bad-month stress test in QuickBooks Online
You need to gather your cash, expenses, and revenue, then model a realistic bad scenario.
- 1Get your current cash
Go to Reports→ “Balance Sheet.” Set the date to today. Note “Total Bank Accounts” under Current Assets.
- 2Get your monthly expenses and revenue
Go to Reports→ “Profit and Loss.” Set it to the last 3 months. Divide Total Income and Total Expenses by 3 for monthly averages.
- 3Check your customer concentration
Go to Reports→ “Sales by Customer Summary.” Set it to the current month. If your top customer is more than 25% of revenue, a late payment from them alone could create a bad month.
- 4Check upcoming large expenses
Look at Reports→ “Accounts Payable Aging Summary” for vendor bills. Think about quarterly taxes, insurance renewals, or equipment needs in the next 60 days.
- 5Model the bad month
In a spreadsheet: take your cash, subtract a full month of expenses, add only 60-70% of your normal revenue (to simulate a revenue dip or late payment), and subtract one surprise cost ($5K-$15K). Is the result positive? By how much?
Total time: about 20 minutes across four reports and a spreadsheet. The hardest part is being honest about what “bad” looks like for your specific business.
How to run a bad-month stress test in Xero
Same process. Different menus.
- 1Get your cash and P&L numbers
Go to Accounting → Reports. Pull the Balance Sheet for your cash position and the Profit and Loss for revenue and expenses over 3 months.
- 2Check customer concentration
Xero does not have a built-in “Sales by Customer” report. Go to Business → Invoices, filter by date range, and export to a spreadsheet. Sort by customer to see concentration. This is the most manual step.
- 3Check payables
Go to Accounting → Reports→ “Aged Payables” for outstanding vendor bills.
- 4Run the scenario in a spreadsheet
Cash minus expenses, plus reduced revenue, minus a surprise cost. If the bottom line is negative, you are one bad month from trouble.
Total time: 20-30 minutes. The customer concentration check in Xero adds time because it requires an export and spreadsheet sort.
Why this check needs to happen before the bad month arrives
The whole point of this stress test is to run it when things are fine. Here is why most owners do not:
- When things are going well, it feels unnecessary. Revenue is good, bills are paid, payroll is covered. Why stress test? Because by the time you need the answer, it is too late to change it.
- It requires combining four different reports. Balance Sheet, P&L, customer sales, and payables. No single report in QuickBooks or Xero answers this question.
- The scenario requires judgment calls.What counts as a “bad month” for your business? The answer is different for a restaurant, an agency, and a contractor. You need to think through the realistic scenarios, not just plug in generic numbers.
Or get your margin of safety checked automatically
Bottomline runs a bad-month stress test automatically every month. It combines your cash, expenses, revenue pattern, customer concentration, and upcoming obligations to determine how much buffer you have.
Bottomline does not just tell you the number. It identifies the specific factors that make you vulnerable: customer concentration, upcoming lumpy expenses, thin cash reserves. That way you know exactly what to address to widen your margin of safety.