Stress-Test Your Model and Explain the Results
A model that balances is a tool, not an answer. Its real value is what happens when you change the inputs. In this final lesson you will run two "what if" scenarios on Brightcup, see results that surprise most beginners, and use AI to turn the numbers into a short summary someone else can act on.
What You'll Learn
- How to run a scenario by changing only the inputs
- Why slower-paying customers can drain cash faster than falling sales
- How to save scenarios side by side
- How to use AI to write a clear model summary, and what to check in it
Scenario 1: a tough market
Coffee bean prices rise and sales stall. Change these inputs only:
- Revenue (C3:E3): 1,000 in every year
- COGS % (C4:E4): 63% in every year
Now look at the results. Your balance check should still be 0 in every year. If it is not, look for a typed number in the statements that duplicates something calculated elsewhere. Even if the check is 0, compare your results to the table below. A typed number can leave the model balanced but with stale figures.
| Downside scenario | Year 1 | Year 2 | Year 3 |
|---|---|---|---|
| Net income | 46.4 | 48.8 | 51.2 |
| Cash from operations | 94.9 | 98.8 | 101.2 |
| Closing cash | 64.9 | 33.7 | 4.9 |
Brightcup is still profitable every year. But cash falls to almost nothing by Year 3. The business makes a profit, yet it is spending 60 on equipment, 50 on debt, and 20 on dividends every year. That is 130 of cash out against about 100 coming in.
This is exactly the kind of finding a model is for. An owner looking only at profit would feel fine. The model shows they need to cut dividends, delay the equipment, or talk to the bank, well before the cash runs out.
Change the inputs back to the base case before the next scenario.
Scenario 2: customers pay slower
Sales are on plan, but large cafe customers start paying later. Change only:
- Receivables % (C12:E12): 20% instead of 10%
| Slow payers scenario | Year 1 | Year 2 | Year 3 |
|---|---|---|---|
| Net income | 82.4 | 96.8 | 111.2 |
| Cash from operations | 9.4 | 123.8 | 138.2 |
| Closing cash | -20.6 | -26.8 | -18.6 |
Net income is identical to the base case. Yet cash goes negative in Year 1. Receivables jump from 100 to 220, which locks up 120 of cash with customers in a single year. In real life, borrowing to cover that gap would add interest, so profit would end up slightly lower too.
This is one of the most common ways small, profitable businesses fail. Negative cash is not possible in real life. It means Brightcup would need an overdraft or new loan. Your "cash never negative" check from the last lesson should now show FALSE.
Save scenarios side by side
Instead of overwriting inputs, a simple approach is:
- Duplicate the sheet and name the copies Base, Downside, and Slow payers.
- Change only the inputs on each copy.
- Add a small summary sheet that pulls closing cash and net income from each one.
Ask AI to help with the summary formulas.
Use AI to write the summary
Most people who read your model will never open it. They will read a paragraph. AI is good at drafting that paragraph, as long as you give it the real numbers.
Check the AI summary before you send it
Read every number in the summary and find it in your model. Look for three common problems:
- Changed numbers. AI sometimes rounds or retypes figures. 89.4 becoming 89 or 94 is a red flag.
- Invented causes. If the summary says "due to rising rent" and rent is not in your model, delete it.
- Overconfidence. A forecast is not a promise. Phrases like "will reach" are better written as "is forecast to reach."
The model is yours. AI helps you explain it.
Where to go next
You have built, linked, debugged, and stress-tested a real 3-statement model. That is the foundation of almost every finance job and finance exam. To go further:
- Take the full Financial Modeling & Valuation course to build a larger model and value a company with a DCF.
- Sharpen your spreadsheet skills with AI-Powered Excel Formulas.
- Try rebuilding the Brightcup model from a blank sheet, without the template. If you can do it in under an hour, you have truly learned it.
Key Takeaways
- Run scenarios by changing inputs only. The balance check should stay at 0.
- A business can be profitable and still run out of cash, through spending, debt repayment, and dividends.
- Slower-paying customers can push cash negative even when profit does not change at all.
- Keep scenarios on separate copies with a summary table so they can be compared.
- Use AI to draft the summary from your real numbers, then check every figure and remove invented causes.