Pay Down Debt or Build a Cash Buffer? Where Spare Cash Should Go

There is £10,000 sitting in the business account that isn't spoken for. One voice says clear the loan — debt is a drag, and every month it costs you interest. The other says hold it — the last quiet month was frightening and you never want to feel that again.

Both pieces of advice are sensible. They just answer different questions, and the argument between them hides the trade that actually matters: repaying debt buys a certain return you cannot take back, while a cash buffer buys options you pay to keep. Which one is right depends less on the interest rate than on how reversible your decision is and how lumpy your income is.

The trade in one line

Money used to repay a term loan is gone. It bought you a real, guaranteed saving — every pound of interest you no longer pay is a pound you keep — but it is not available on the day a customer pays sixty days late.

Money sitting in the account earns you little or nothing and costs you the interest you are still paying on the debt you did not clear. What it buys instead is the ability to keep trading through a bad month without asking anyone's permission.

So the question is not "which is more responsible." It is: how much are you willing to pay for the option to change your mind?

What a cash buffer actually is

A buffer is not "some savings." It is a specific number: the committed cash your business must pay out over a defined stretch of time even if very little comes in.

Add up your genuinely committed monthly outgoings:

Note what is not in that table: stock you would not buy if sales stopped, contractor work you can pause, marketing you can switch off. A buffer covers what you cannot switch off, not your whole cost base. Working from your total spend inflates the target so badly that most owners give up on it.

How many months? There is no universal answer, but a workable rule of thumb runs like this: one month of committed costs is the floor for a business with steady, diversified income; three months is the realistic target for most; and more than that starts to make sense only when your income is seasonal, project-based, or concentrated in a few customers. A business where one client is 40% of revenue needs a bigger buffer than a business with two hundred customers, at the same revenue.

If you have never mapped your committed costs against the timing of money coming in, do that first — the cash flow guide walks through it, and the answer often changes what you thought you needed.

What repaying debt actually returns

Clearing debt has a return you can calculate exactly, which is rare and genuinely attractive: it equals the interest rate on the debt you clear. Pay off a facility charging 14% and you have earned 14% on that money, with no market to be right about.

Three things complicate that clean picture, and they are where the real decision lives.

Early repayment may cost you. Some facilities charge a fee for settling early, and some fixed-cost products bake the whole finance charge in whether you settle early or not. If the charge is fixed at the start, early repayment saves you nothing at all — you are just prepaying. Read the settlement terms before you assume a saving exists.

A lump-sum payment may not reduce your monthly payment. On many term loans an overpayment shortens the term instead. That is real money saved over the life of the loan, but it does nothing for next month's cash position — which may be exactly the problem you were trying to solve.

Interest is usually a deductible business cost, which means the effective rate you are saving is lower than the headline rate. How much lower depends on your structure and your position, and that is a question for your accountant rather than a blog.

The asymmetry nobody mentions

Here is the part that decides most of these cases: you can almost always repay debt later, but you cannot always borrow later.

Credit is offered most freely to businesses that don't need it. The moment your trading dips — the moment you actually need the money — is the moment facilities get reviewed, limits get trimmed, and new applications get declined. A buffer you funded in a good month is available in a bad one. A loan you were counting on may not be.

This is why "I'll clear the loan and keep the credit line for emergencies" is riskier than it sounds. An undrawn facility is a promise from someone else, and it is a promise that can be withdrawn. Cash in your own account cannot be.

Revolving or term? It changes the answer

This is the single most useful distinction, and it is usually left out of the debate entirely.

Revolving debt — an overdraft, a business credit line, a card — can be repaid and redrawn. Paying it down is reversible: you save interest while the balance is low, and the money comes back if you need it. For revolving debt, the choice between repaying and holding cash barely exists. Pay it down, keep the facility open, and treat the undrawn limit as part of your buffer with a discount applied for the fact that a lender can pull it.

Term debt — a fixed loan, equipment finance, an asset purchase — is one-directional. Once paid, it is paid. Overpaying term debt is a genuine decision, and it should be made only from money above your buffer.

Which situation suits each

Fund the buffer first when:

• Your revenue is seasonal, project-based, or paid in irregular lumps.
• One or two customers make up a large share of your income.
• You have no credit facility, or it is personally guaranteed and you would rather not draw on it.
• Your business is young, and you have not yet seen a full year of its worst month.
• Your debt is cheap, fixed, and comfortably affordable from normal trading.

Repay debt first when:

• Your buffer already covers your committed costs for the period you decided on.
• The debt is expensive — high-rate cards, short-term advances, anything you would not take out again today.
• The debt is revolving, so repayment is reversible.
• A refinance or a facility review is coming and a lower balance improves how you look to a lender. The business financing guide covers what lenders actually weigh.
• The repayment is squeezing your monthly cash so hard that it is causing the shortfalls you keep firefighting — this is a common pattern in businesses that are profitable but broke.

The order most businesses should follow

For the majority of small businesses, this sequence beats either extreme:

1. Clear anything expensive and revolving down to zero. Nothing beats not paying a high rate.
2. Fund a one-month buffer from committed costs, not total costs. This is the step that stops small problems becoming emergencies.
3. Split what's left — a fixed share to the buffer, a fixed share to the most expensive remaining debt, decided once and automated. Splitting removes the monthly argument with yourself, which is worth more than the small optimisation you lose.
4. Stop at the buffer target you set, then send everything above it at debt. A buffer that grows without limit is just idle capital with a comfortable name.

Track the buffer as a number of months rather than a balance, so it rises automatically as your costs do. It belongs alongside the other financial KPIs worth tracking.

Signs you got the balance wrong

• You are paying a high rate on a card while holding six months of costs in cash. That is expensive comfort.
• You cleared a loan and now delay supplier payments in slow weeks. You converted flexible cash into fixed savings.
• You keep "the buffer" in the same account you spend from and cannot say what it is today. It isn't a buffer; it's a float.
• Your buffer target was set years ago and your payroll has doubled since.

FAQ

Should I use my buffer to pay a tax bill? No — a known tax bill is not an emergency, it is a scheduled cost. Set that money aside separately as it accrues, ideally in its own account, and check the timing and amounts with your accountant.

Is it worth repaying a very cheap loan early? Rarely, if the rate is low and the payment is comfortable. Cheap, long, fixed debt is one of the more useful things a small business can hold, and the flexibility of keeping the cash usually outweighs the interest saved.

Does an unused overdraft count as my buffer? Partly, and only with a discount. A facility can be reduced or withdrawn, often at the worst moment. Treat it as a second line of defence behind real cash, never as a replacement for it.

Where should the buffer sit? In a separate business account, so it is visible, countable, and not accidentally spent. Instant access matters far more than the interest it earns.

We have no spare cash at all. What then? Then the priority is neither — it is the gap between when you pay and when you get paid. Faster invoicing, deposits, and better payment terms free cash without needing any spare in the first place.

Decide the size of your worst realistic month before you decide anything else. Fund the buffer to that number, keep it somewhere you can see it, and send every pound above it at your most expensive debt. For calculators and plain-English guides to the rest of your numbers, visit SortProfit.