Ask most owner-led business owners how much cash should sit in the account and they will give you a number quickly. Ask how they arrived at it and the confidence tends to drop away. It is usually a rough sense of what feels safe, a figure the balance once dropped to during a rough patch that scared everyone in the business, or a multiple of monthly expenses picked up somewhere and never actually tested against how the business itself behaves.
That guess tends to go wrong in one of two directions. Some businesses run persistently thin, treating a predictable seasonal trough as a fresh emergency every time it arrives. Others carry more cash than their own volatility ever calls for, and that surplus sits idle, quietly reducing the return the business generates on everything it owns, without anyone ever framing it as a deliberate decision.
The number that actually protects a business is not a rule of thumb borrowed from somewhere else. It is specific to how far that business’s own cash position genuinely moves between its best month and its worst, and most owners have never sat down and measured that gap directly. That is exactly why the buffer question usually gets answered with a guess.
Why Three Months of Expenses Rarely Fits the Business Holding It
Generic financial advice tends to recommend a flat multiple of monthly expenses, three months being the figure that circulates most often. It is a reasonable starting point for a household budget. It is a poor fit for a business, because it assumes every business experiences the same shape of cash flow, and owner-led businesses rarely do.
A business with lumpy, milestone-based income, a construction firm waiting on progress claims, or an allied health practice riding the private health fund rush in June before a flatter July, experiences a far wider swing between its best and worst months than a business collecting steady monthly fees from a stable client base. The pattern we typically see is that businesses with the least predictable income are often the ones running the thinnest buffer, precisely because nobody has ever measured what their real trough looks like against their real average.
The Cost of Guessing Wrong in Either Direction
Running too thin has a cost that shows up in decisions, not just in stress. A business with no genuine buffer treats every predictable seasonal dip as a crisis, which pushes it toward defensive choices: delaying a supplier payment that damages a relationship built over years, turning down a good contract because there is no room to fund the work upfront, or reaching for expensive short-term finance at the exact moment its bargaining position is weakest.
Running too thick has a quieter cost, but it is still a cost. Cash sitting well beyond what the business’s own volatility requires earns close to nothing in a transaction account, and that gap between what the cash is earning and what it could be earning elsewhere in the business, paying down debt, funding growth, or being returned to the owner, is a return the business is simply forfeiting. Most owners carrying a large buffer have never actually been asked to justify the number, which is usually the clearest sign it was never calculated in the first place.
Sizing the Number to the Business You Actually Run
The more reliable starting point is the bank statement, not the P&L. Looking back across the last twelve to twenty four months of actual account movements, rather than the smoothed monthly figures in the accounts, shows the real low point the business reached relative to its typical balance. That gap, not an assumed average, is the genuine evidence of how much volatility the business experiences, and the buffer should sit comfortably above it.
It is also worth asking whether the whole buffer needs to sit as idle cash at all. A portion of it can often be covered more cheaply by a properly sized standby facility, reviewed for its actual terms, covenants and pricing through a Banking and Facility Review, which costs interest only when drawn rather than tying up cash that could otherwise be working somewhere in the business. Treating the buffer question as part of the business’s broader cash flow discipline, rather than a number set once and forgotten, is what keeps it accurate as the business changes shape.
This is one of the more concrete exercises that tends to happen early in an ongoing fractional CFO partnership, because it replaces a guess that everyone has quietly been relying on with a number the business can actually explain. ProfitPulse works with owner-led businesses across Queensland, Sydney and Victoria on exactly this kind of calculation. If your business has never actually tested its cash buffer against its own numbers, book a discovery call with ProfitPulse and it can be worked through in a single session.
Frequently asked questions
How much cash should an Australian small business keep in reserve?
There is no single figure that fits every business, whatever generic advice suggests. The right buffer reflects how far your own cash position moves between its best and worst months, which varies enormously by industry and payment terms. Measuring your actual low point against your typical balance over the last two years, as part of ongoing cash flow discipline, gives a far more reliable number than a flat rule of thumb.
What is the risk of holding too much cash in a business bank account?
Cash sitting well beyond what the business’s own volatility requires earns very little in a transaction account. The gap between that return and what the same money could achieve elsewhere, paying down debt, funding growth, or being returned to the owner, is a cost the business is quietly absorbing, even though it never appears as a line item anywhere.
How do I calculate the right cash buffer for a seasonal business?
Start with actual bank account movements over the last twelve to twenty four months rather than the smoothed figures in the profit and loss statement, and find the lowest point the balance reached relative to its typical level. That gap is the real evidence of your seasonal swing, and the buffer should sit comfortably above it rather than above an assumed average month.
Is it better to hold cash or have a line of credit for emergencies?
Often a combination works better than relying on cash alone. A properly sized standby facility, checked through a Banking and Facility Review, costs interest only when it is actually drawn, whereas idle cash earns little regardless of whether it is needed. Covering part of the buffer through a facility can free up cash that would otherwise sit unused for most of the year.
How often should a business revisit its cash buffer target?
At least once a year, and again after any material change, a new large customer, a shift in payment terms, or a move into a more seasonal line of work. A buffer sized correctly for the business two years ago can be badly out of step with the business it has become, particularly after a period of growth.
Does a fractional CFO help decide how much cash a business should hold?
Yes, and it is often one of the first concrete exercises in a new fractional CFO partnership. Rather than inheriting a figure nobody can quite explain, the business gets a buffer sized against its own trading history, along with a view on whether part of it would be better held as facility headroom than as idle cash.
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