How SMEs Can Calculate How Much Cash to Keep Before Funding a Major Investment
A healthy bank balance can make a major business investment appear easier to afford than it really is.
Suppose an SME has:
S$500,000 in the bank
and is considering a:
S$180,000 investment
The immediate reaction may be:
“We have more than enough cash. We can simply pay for it.”
But the S$500,000 is not necessarily surplus cash.
Part of it may already be needed for:
- Payroll
- Supplier payments
- Rent
- GST and tax obligations
- Inventory purchases
- Existing financing repayments
- Seasonal cash-flow gaps
- Unexpected operating expenses
The more useful question is therefore not:
“How much cash do we have?”
It is:
“How much cash can we commit to this investment while still leaving the existing business with enough liquidity to operate safely?”
Answering that question requires an SME to calculate an operating cash floor before deciding how much of its reserves are genuinely available for investment.
1. Bank balance and surplus cash are not the same thing
A bank account shows how much cash the company has at a particular moment.
It does not show how much of that cash is already economically committed.
Consider an SME with:
S$500,000 in cash
During the next month, it expects to pay:
| Upcoming Commitment | Amount |
|---|---|
| Payroll and employer costs | S$90,000 |
| Suppliers | S$120,000 |
| Rent and operating expenses | S$35,000 |
| Existing financing repayments | S$20,000 |
| Tax and other scheduled payments | S$25,000 |
| Total | S$290,000 |
Some customer collections may arrive before those payments are due.
But the example demonstrates why S$500,000 in the bank should not automatically be treated as S$500,000 available for investment.
2. Start with the existing business before adding the investment
The first step is to forecast what happens to cash if the SME does not make the proposed investment.
This creates a baseline.
Suppose the company expects the following closing cash balances over the next six months:
| Month | Projected Closing Cash Before New Investment |
|---|---|
| Month 1 | S$470,000 |
| Month 2 | S$420,000 |
| Month 3 | S$360,000 |
| Month 4 | S$320,000 |
| Month 5 | S$350,000 |
| Month 6 | S$400,000 |
The business begins with substantial cash.
However, its lowest projected balance is:
S$320,000 in Month 4
That low point matters more than the current S$500,000 bank balance when deciding how much cash can safely be removed for a major investment.
3. Identify why the cash balance falls
A falling balance is not automatically a problem.
Management should understand what creates the low point.
Possible reasons may include:
- Seasonal inventory purchases
- Annual insurance or licence payments
- GST or tax payments
- Bonuses
- Customer payment timing
- Supplier payment cycles
- Existing project expenditure
If the Month 4 low point is predictable and temporary, the business can plan around it.
If management cannot explain why cash falls, the forecast may require further investigation before a new investment is added.
4. Set a minimum operating cash floor
An SME may decide that it does not want cash to fall below a certain operating level.
This is the company’s minimum cash floor.
There is no single cash reserve amount that is appropriate for every SME.
The appropriate level depends on factors such as:
- Monthly fixed expenses
- Revenue stability
- Customer payment behaviour
- Supplier terms
- Inventory requirements
- Seasonality
- Existing debt commitments
- Access to additional liquidity
- Volatility of the industry
- Potential emergency expenditure
For the example in this article, assume management decides that the existing business should maintain at least:
S$230,000
of cash under normal expected conditions.
This is an internal planning assumption for the example, not a universal recommendation.
5. Calculate the available cash above the operating floor
The lowest projected cash balance without the investment is:
S$320,000
The minimum operating cash floor is:
S$230,000
The amount available above that floor is therefore:
S$320,000 – S$230,000 = S$90,000
Under these assumptions, approximately S$90,000 is the maximum amount the SME could remove from the forecast without pushing the lowest expected cash balance below its chosen S$230,000 floor.
This is a very different conclusion from looking at the current S$500,000 balance and assuming the company can comfortably spend S$180,000.
6. Do not calculate surplus cash using today’s bank balance alone
A tempting calculation would be:
Current cash:
S$500,000
Minimum desired cash:
S$230,000
Apparently available cash:
S$270,000
But this ignores the natural fall in cash expected during the next several months.
The forecast shows the company may already fall to S$320,000 without making the investment.
Therefore, the more useful available-cash figure in this example is S$90,000, not S$270,000.
Surplus cash should be calculated against the expected low point, not simply today’s high point.
7. Add the investment and see what happens to the low point
Suppose the SME is considering a:
S$180,000 equipment and expansion investment
If the full S$180,000 is paid immediately from internal cash, the projected balances become approximately:
| Month | Baseline Cash | After S$180,000 Cash Investment |
|---|---|---|
| Month 1 | S$470,000 | S$290,000 |
| Month 2 | S$420,000 | S$240,000 |
| Month 3 | S$360,000 | S$180,000 |
| Month 4 | S$320,000 | S$140,000 |
| Month 5 | S$350,000 | S$170,000 |
| Month 6 | S$400,000 | S$220,000 |
The lowest projected balance falls to:
S$140,000
This is:
S$90,000 below
the S$230,000 operating floor management wanted to preserve.
The company can technically pay for the project.
But under its own liquidity policy, it cannot comfortably fund the entire project from cash.
8. Being able to pay and being able to afford are different concepts
This distinction is important.
The SME has S$500,000 in the bank and can physically make a S$180,000 payment.
However, affordability should also consider what the company looks like after the money leaves.
A major investment may be affordable in the long term while creating excessive short-term liquidity risk.
This is why investment analysis should consider both:
- Expected return from the investment
- Liquidity remaining after the investment
9. Calculate the amount that can safely be self-funded
The example indicates that approximately:
S$90,000
can be removed while preserving the chosen operating floor under the base forecast.
The total investment is:
S$180,000
The remaining amount is:
S$180,000 – S$90,000 = S$90,000
This does not automatically mean the SME should borrow S$90,000.
It means the business has identified a funding gap that must be solved somehow if it wants to proceed while maintaining the chosen liquidity floor.
10. A funding gap can be solved in more than one way
Possible approaches may include:
- Using part internal cash and part financing
- Phasing the investment
- Negotiating staged supplier payments
- Delaying part of the project
- Reducing the initial project scope
- Using future operating cash flow to fund later stages
The financing decision should therefore come after the liquidity analysis rather than before it.
11. Cash has no interest charge, but using it is not financially costless
Using internal cash avoids an explicit borrowing cost.
That is a real advantage.
However, cash also provides flexibility.
Once S$180,000 has been committed to an investment, it may no longer be available for:
- An unexpected equipment breakdown
- A customer payment delay
- A sudden inventory opportunity
- An emergency supplier payment
- A new high-margin customer order
- An unexpected decline in revenue
The economic cost of using cash therefore includes the flexibility and future options the company gives up.
This is the opportunity cost of self-funding.
12. Financing has an explicit cost but may preserve liquidity
External financing creates its own trade-off.
The SME may preserve more cash, but it takes on:
- Interest or financing cost
- Fees
- Regular repayments
- Potential guarantees or security
- Additional contractual obligations
The question is therefore not:
“Cash or financing: which one is free?”
Neither choice is economically neutral.
The decision is about whether preserving liquidity is valuable enough to justify the financing cost and obligations.
13. Compare three possible funding structures
For the S$180,000 investment, management might compare:
| Option A | Option B | Option C | |
|---|---|---|---|
| Funding structure | 100% internal cash | S$90,000 cash + S$90,000 financing | Mostly financing |
| Cash preserved initially | Lowest | Moderate | Highest |
| Financing cost | None | Moderate | Highest |
| Repayment obligation | None | Moderate | Highest |
| Liquidity flexibility | Lowest | Higher | Highest initially |
There is no automatic winner.
The company needs to evaluate both the cash reserve preserved and the repayment burden created.
14. Financing repayments must be added back into the cash forecast
Preserving S$90,000 today does not mean the business permanently retains S$90,000.
If the SME finances that amount, future repayments reduce cash.
Suppose the proposed financing creates an illustrative repayment of:
S$4,000 per month
The SME should rebuild the month-by-month projection to include those repayments.
Otherwise, management may overstate how much liquidity financing actually preserves.
This is also why Debt Service Coverage Ratio and broader repayment-capacity analysis can be useful when new debt is introduced.
15. Include the investment’s expected cash benefit too
The analysis should not assume that the investment only consumes cash.
If the investment is commercially sound, it should eventually create an economic benefit.
Suppose the S$180,000 project is expected to generate:
S$9,000 of additional monthly operating cash
after implementation.
However, the benefit only begins in:
Month 4
The project therefore creates cash pressure first and financial benefit later.
A good forecast includes both sides.
16. Project return does not eliminate the need for a cash buffer
An investment can have an attractive expected return and still create a dangerous short-term liquidity position.
Suppose management expects the project to generate:
S$108,000 of additional operating cash per year
once fully operational.
That may make the S$180,000 investment commercially attractive.
But if paying S$180,000 today causes the company to fall below the cash required for payroll or suppliers next quarter, the long-term return does not solve the immediate problem.
Return on investment and liquidity are related but separate questions.
17. A lower cash balance increases exposure to forecasting errors
Cash forecasts are estimates.
Suppose the fully self-funded investment leaves the SME with a lowest projected balance of:
S$140,000
If a major customer then pays:
S$60,000 later than expected
the effective cash position may temporarily fall much further.
A company operating very close to its minimum liquidity requirement has less capacity to absorb forecasting errors.
This is one reason preserving cash can have value even when financing costs money.
18. The appropriate cash floor should reflect revenue volatility
Two SMEs with the same monthly expenses may reasonably choose different liquidity buffers.
Consider:
Business A
- Recurring contracts
- Stable customer collections
- Predictable supplier expenditure
Business B
- Project-based revenue
- Large customer concentration
- Irregular collections
- Seasonal inventory purchases
Business B may need more liquidity protection because its cash flow is less predictable.
This is why a fixed rule such as “every SME should hold exactly three months of cash” can be too simplistic.
The reserve should reflect the actual financial behaviour of the company.
19. Customer concentration can justify a larger buffer
Suppose 45% of an SME’s revenue comes from one customer.
The company may have strong historical cash flow.
However, losing or experiencing late payment from that one customer could have a disproportionate effect on liquidity.
Management may therefore decide that retaining additional cash is worth more than aggressively self-funding a new investment.
Businesses can review customer concentration before taking financing when considering this risk.
20. Inventory-heavy businesses may also need more operating cash
An SME that needs to purchase substantial inventory before making sales may require more cash than a service business with low working-capital requirements.
Suppose the company periodically needs:
S$120,000
for inventory replenishment.
If management ignores that cycle when setting its cash floor, it may classify cash as “surplus” shortly before the business needs it for stock.
SMEs can also review inventory financing and stock turnover when analysing how much cash is routinely tied up in inventory.
21. Existing debt reduces financial flexibility
Financing repayments continue even when sales weaken.
An SME with significant existing debt may therefore choose to retain a larger cash buffer than an otherwise similar debt-free company.
Suppose the business already pays:
S$25,000 per month
in financing commitments.
Adding another project should be evaluated not only against operating costs but against those fixed debt-service obligations.
Cash retained today provides additional ability to meet those commitments during weaker months.
22. Phasing an investment can reduce the peak cash requirement
A S$180,000 project does not always need to be paid entirely at once.
Suppose the investment can be divided into:
| Stage | Cost |
|---|---|
| Phase 1 | S$70,000 |
| Phase 2 | S$60,000 |
| Phase 3 | S$50,000 |
| Total | S$180,000 |
If Phase 2 and Phase 3 occur after the project begins generating positive cash flow, the business may be able to self-fund more of the later stages without pushing its cash balance below the minimum floor.
Staging can therefore change the funding requirement without changing the total project cost.
23. Supplier payment terms can change whether financing is needed
Suppose the S$180,000 investment involves purchasing equipment.
If the supplier requires the full amount upfront, cash pressure is immediate.
If the supplier agrees to:
- 30% on order
- 40% on delivery
- 30% after commissioning
the investment cash outflow is spread across several periods.
This may reduce the need for external financing while preserving a healthier operating balance.
The lesson is that funding structure should be evaluated after commercial payment terms are understood.
24. Stress-test the minimum cash floor
The S$230,000 operating floor in the example is based on management’s normal expected conditions.
Before committing surplus cash, the SME should ask what happens if:
- Revenue is 15% below forecast
- A major customer pays 30 days late
- Supplier costs increase
- Inventory requirements rise unexpectedly
- The investment itself costs more than budgeted
- The project takes longer to produce benefits
If a realistic downside scenario causes the company to fall below the cash required for normal operations, management may decide to preserve more liquidity.
SMEs can explore these scenarios in more depth by stress-testing their cash flow before taking financing.
25. Do not keep excessive cash without considering its purpose
Protecting liquidity does not mean an SME should automatically keep every dollar in the bank indefinitely.
Cash that is genuinely surplus to operating requirements may be able to support:
- Productive equipment
- Expansion
- Inventory for proven demand
- Technology
- Debt reduction
- Other business investments
The objective is not maximum cash retention.
It is maintaining enough liquidity while using genuine surplus capital productively.
26. Review the cash floor regularly
The minimum operating balance should not remain unchanged forever.
It may need to rise if:
- Payroll increases
- The company carries more inventory
- Customer payment periods lengthen
- Debt repayments increase
- Revenue becomes less predictable
It may potentially fall if:
- Cash collections become more predictable
- Working-capital efficiency improves
- Debt is repaid
- Fixed commitments fall
- The business gains reliable access to additional liquidity
The cash floor should follow the business rather than being chosen once and forgotten.
27. Build a simple cash-allocation worksheet
Before funding a major investment, management can summarise the decision in one table.
| Item | Amount |
|---|---|
| Current cash balance | S$500,000 |
| Lowest projected balance before investment | S$320,000 |
| Chosen minimum operating cash floor | S$230,000 |
| Cash potentially available above floor | S$90,000 |
| Total proposed investment | S$180,000 |
| Remaining funding requirement | S$90,000 |
The worksheet does not dictate how the remaining S$90,000 should be funded.
It identifies the financial problem clearly.
Management can then compare financing, staging, supplier terms or other funding options.
28. Questions SME owners should ask before using cash reserves for a major investment
Before committing a large amount of company cash, management can ask:
- How much cash do we have today?
- What major payments are already committed?
- What does our cash balance look like over the next six to twelve months without the investment?
- What is the lowest projected cash balance?
- Why does that low point occur?
- What minimum operating cash level do we want to preserve?
- What business risks justify that level?
- How much cash is genuinely available above that floor?
- What happens to the lowest balance if the project is fully self-funded?
- How much of the investment can safely be funded internally?
- What funding gap remains?
- Could the project be phased?
- Could supplier payment terms spread the cash requirement?
- What financial return is the project expected to generate?
- When will that benefit begin?
- What liquidity do we give up by self-funding?
- What financing cost and repayments would arise if we borrow instead?
- How do financing repayments change the future cash forecast?
- What happens if customer payments arrive late?
- What happens if the investment costs more than expected?
- Would the existing business remain financially stable under a reasonable downside scenario?
- Are we preserving cash for a defined operating reason or simply because having a large bank balance feels safer?
- Are we using genuine surplus cash productively?
If management cannot identify how much cash is genuinely surplus to normal operating requirements, it may be too early to decide how much of a major investment should be self-funded.
Final thoughts
The amount sitting in an SME’s bank account is not automatically the amount available for investment.
A business may have S$500,000 in cash while already needing much of that money for payroll, suppliers, inventory, taxes, debt repayments and predictable seasonal movements.
This is why major investment decisions should begin with the existing business.
First forecast what cash would look like without the investment.
Then identify the lowest expected balance.
Then determine how much liquidity management wants to preserve for normal operations and reasonable uncertainty.
The difference between the projected low point and that minimum operating floor provides a much more useful estimate of how much cash may be available for investment.
In the simplified example used throughout this article:
Current bank balance:
S$500,000
Lowest expected balance before investment:
S$320,000
Chosen operating cash floor:
S$230,000
Cash potentially available for the project:
S$90,000
That is very different from assuming the company can freely use hundreds of thousands of dollars simply because the bank balance is currently high.
The strongest capital-allocation decision is therefore not:
“We have the cash, so we should use it.”
Nor is it:
“Financing preserves cash, so we should always borrow.”
It is:
“We know how much liquidity the existing business needs, how much cash is genuinely surplus, what the investment is expected to return, and whether preserving additional liquidity is worth the cost and obligations of external financing.”
Cash reserves are valuable because they provide resilience and flexibility.
But cash can also support productive investment.
The objective is not to maximise either borrowing or cash retention.
It is to allocate capital without weakening the business that capital is meant to grow.