It surprises many dentists that a thoroughly profitable practice can still need to borrow. The reason is timing: a practice pays its staff and rent steadily through the month while its income and its largest outflows, tax, NHS clawback, equipment costs, arrive unevenly and often in lumps. Working capital is the cash that bridges those gaps, and when the practice's own buffer is not enough, a working-capital facility does the job. Used well, it smooths the timing of healthy cash flows and its interest is deductible. Used badly, to prop up an unprofitable practice, it deepens the very problem it appears to solve.
This guide explains working capital for a dental practice: why even a profitable one needs it, the main facilities available, overdrafts, revolving credit, short-term loans and asset finance, when each fits, and the tax treatment, which is that interest and fees on a facility used for the trade are generally deductible. The aim is to help you choose the right facility for the right reason, and to keep it firmly in its proper role as a tool for timing, not a substitute for profit.
What working capital is for a dental practice
Working capital is the cash a practice needs to fund its day-to-day operations between the points at which money comes in and money goes out. Staff wages, rent, materials and loan repayments fall due steadily; income arrives on its own rhythm; and big outflows like tax and clawback land periodically. The space between these flows is where working capital lives. A practice with ample cash holds its working capital as a buffer; one with tighter cash uses a facility to cover the gaps. Either way, the function is the same: to keep the practice able to meet its commitments smoothly regardless of the uneven timing of its cash flows. Crucially, this is a question of timing, not of whether the practice is profitable.
Why even a profitable practice needs it
The key insight is that profit and cash timing are different things, a theme we develop in our guide to cash-flow management and tax reserves. A practice can be comfortably profitable over the year yet face a particular month where a large tax payment, a clawback recovery, a quiet seasonal period and the usual fixed costs all coincide. In that month, even a profitable practice can be short of cash. Working capital, held or borrowed, covers that short-term gap until income catches up. Far from being a sign of weakness, having appropriate working capital in place is a mark of a well-run practice that understands its own cash rhythm and has prepared for the predictable pinch points rather than being caught out by them.
Overdraft versus revolving facility versus short-term loan
There are several ways to provide working capital, and they suit different needs.
- An overdraft lets you draw your business account below zero up to an agreed limit, with interest charged on the amount actually used. It is flexible and simple, well suited to small, short, unpredictable timing gaps.
- A revolving credit facility is a pre-agreed pool you can draw down and repay repeatedly up to a limit. It suits slightly larger or more structured working-capital needs and gives more certainty than an on-demand overdraft.
- A short-term loan provides a fixed sum repaid over a defined period, which can fit a known, one-off need rather than a recurring gap.
The right choice depends on how large, how frequent and how predictable your working-capital need is. The flexible facilities flex with you; the fixed loan suits a defined purpose. Matching the structure to the actual pattern of need keeps the cost down and the facility useful.
Working capital for a new practice owner
The working-capital need is sharpest in the first year of ownership, which is worth flagging for anyone buying a practice. A new owner takes on the full running costs from day one, often alongside acquisition loan repayments, while the income and the practice's rhythm are still settling and any transition wobble works through. The early months can therefore be cash-tight even for a fundamentally healthy practice, simply because the new owner has not yet built a buffer and is meeting every cost while learning the business. A sensibly sized working-capital facility, arranged as part of the acquisition rather than scrambled for later, bridges this settling-in period and prevents an avoidable early crisis. Our guide to financing a practice acquisition stresses leaving room in the plan for working capital, and this is exactly why: the first year is when the practice has the most outgoings and the least buffer, so the facility earns its keep most clearly then. A new owner who has planned for working capital starts from a position of control rather than from a scramble.
Invoice and private-fee finance
A practice with significant private fee income has another option. Where fees are invoiced and not yet paid, or plan income is due, certain facilities can advance cash against those receivables, smoothing the gap between doing the work and being paid. Whether this suits depends on the practice's billing pattern and on the cost of the facility against the benefit it provides. For a practice with a long lag between treatment and payment, advancing against receivables can meaningfully ease working capital; for one paid promptly, it may not be worth the cost. As with other working-capital borrowing, the interest and fees on a facility used for the trade are generally deductible. It is one tool among several for bridging a private-income timing gap.
Asset finance to free up working capital
One of the most effective ways to protect working capital is to avoid tying cash up in equipment in the first place. Financing equipment through hire purchase or leasing, rather than buying outright, keeps cash in the business for day-to-day needs. The tax treatment varies by method: hire purchase generally allows capital allowances on the asset, with the interest element separately deductible, while a lease gives a deductible rental rather than allowances. Our guide to equipment finance and its tax implications sets out the methods in detail. The working-capital point is simple: spreading the cost of equipment over time, rather than paying cash up front, leaves more cash available for the timing gaps that working-capital facilities otherwise have to cover, which can be the more valuable outcome when cash is tight.
How NHS payment timing shapes the need
For an NHS-involved practice, the structure of the contract itself shapes the working-capital need in a specific way. The smooth monthly NHS payment is helpful, providing a predictable base of income, but the year-end reconciliation introduces a lumpy element: a clawback below 96% delivery recovers cash, often months after the income was received and spent. So the very feature that smooths NHS income through the year, the steady monthly payment, sets up a potential lump-sum outflow at reconciliation. A practice that has not reserved for a possible clawback may need working capital to meet it, which is one of the clearest examples of a genuine timing gap that a facility is designed to bridge. Understanding how the NHS payment cycle and reconciliation interact, as our guide to cash flow and tax reserves sets out, lets an owner anticipate the working-capital need rather than discover it when the clawback lands.
The relationship between working capital and growth
Working capital is not only about surviving timing gaps; it also enables growth, and a practice that wants to expand needs to think about it deliberately. Taking on a new associate, adding a surgery, increasing private marketing or extending opening hours all cost money before they generate the extra income they are meant to produce. That gap between investing in growth and reaping it is a working-capital need, and a practice that funds growth purely from its day-to-day cash can find itself squeezed just as the expansion should be paying off. Matching a sensible working-capital facility to a growth plan lets a practice invest ahead of the return without strangling its everyday cash flow. The key, as ever, is that the facility funds a timing gap with a clear payoff, the lag before growth income arrives, rather than an open-ended subsidy. Growth that genuinely lifts profit justifies the bridging cost; growth that never quite pays off does not, which is why a growth plan should be costed before it is financed.
The tax: facility interest and fees are deductible
The tax treatment of working-capital finance is favourable and straightforward. Where the overdraft or facility is for the trade, the interest and the facility or commitment fees are generally deductible: for a company under the loan-relationship rules, and for an unincorporated practice under the trading-expense rules. So the cost of borrowing to bridge genuine business timing gaps reduces your taxable profit. As with all borrowing, the deductibility follows the use of the money: a facility used for genuine business working capital qualifies, while any portion drawn for personal purposes would not. Keep the facility clearly for business use and the relief is clean. This deductibility is one reason a modest, well-priced facility used for timing is an efficient way to manage cash, since the taxman effectively shares part of the cost.
Secured versus unsecured facilities
Working-capital facilities come secured or unsecured, and the distinction affects both cost and risk. A secured facility is backed by a charge over practice assets or, sometimes, a personal guarantee, which usually means a lower cost because the lender's risk is lower, but it puts assets, or you personally, on the line if things go wrong. An unsecured facility carries no such charge and is simpler to put in place, but typically costs more and is offered in smaller amounts. For a routine working-capital need, the choice is a balance between the cheaper cost of a secured facility and the lower personal exposure of an unsecured one. Many practices already have security granted to their main lender from the acquisition borrowing, which can make adding a secured working-capital line straightforward. As with any borrowing that involves a personal guarantee, understand the exposure before signing, because a facility meant to smooth timing should not quietly put your personal assets at risk for a routine cash gap.
Building a buffer instead of borrowing
The strongest position is not to need a facility at all, by holding a cash buffer built from the practice's own profits. A practice that reserves deliberately, for tax, for clawback, and for a working-capital cushion, can bridge most timing gaps from its own resources, borrowing only for the unusual or the large. Building such a buffer takes discipline and time, but it is cheaper than borrowing, carries no interest cost or security risk, and gives the owner genuine independence from lenders for day-to-day cash. The sensible aim for most practices is a combination: a self-funded buffer for the ordinary timing gaps, plus a modest agreed facility held in reserve for the larger or less predictable needs. That way the facility is there when genuinely required but rarely drawn, keeping its cost low and its role firmly as a backstop rather than a crutch. A practice that has built its own buffer uses its facility the way it should be used, occasionally and briefly, rather than living in it.
Cost of finance versus cost of running short
A useful way to think about working-capital finance is to weigh the cost of the facility against the cost of running short without it. Running short has real costs: missed supplier discounts, late-payment problems, the stress and distraction of scrambling for cash, and in the worst case an inability to meet payroll or a tax bill. A modest, deductible facility that prevents all of that can be cheap insurance against a disproportionately damaging event. The judgement is not whether borrowing has a cost, it does, but whether that cost is smaller than the cost and risk of being caught short. For genuine timing gaps, a sensibly sized facility usually wins that comparison comfortably.
Reading the warning signs in your own cash
A practice should learn to read the warning signs that distinguish a healthy use of working-capital finance from a developing problem. A facility that is drawn and repaid, returning to zero between uses, is working as intended. A facility that is creeping steadily higher each month, or that never comes back down, is a red flag that the practice may be funding a structural shortfall rather than a timing gap. Other signs include relying on the facility to meet routine commitments like payroll, rather than occasional ones; using it to pay one debt with another; and an inability to forecast when it will next be clear. Spotting these early, from the monthly cash KPIs that our guide to the financial KPIs every owner should track describes, lets an owner investigate the underlying cause while it is still small. The facility itself is neutral; how it behaves over time tells you whether the practice is managing timing well or quietly slipping into a profitability problem that finance cannot solve.
Matching the facility to the need
The single most important discipline is to match the facility to the need, in both size and type. Size it to bridge the worst realistic timing gap with some margin, no more, because an oversized facility carries cost and can tempt over-reliance. Choose the type to fit the pattern: an overdraft for small unpredictable gaps, a revolving facility for larger structured needs, a short-term loan for a one-off, asset finance to keep equipment off the cash budget. The tool that tells you how big the gaps are is a rolling cash forecast, which our cash-flow guide describes, because it shows the months where outflows coincide and reveals the true size of the working-capital need. Sizing and structuring the facility from a real forecast, rather than a guess, keeps it useful and economical.
A worked example
Take a practice facing a quarterly tax payment that falls in a seasonally quiet month.
- The gap. The tax payment and the usual fixed costs fall due while income is temporarily low, creating a short-term shortfall even though the practice is profitable over the year.
- The bridge. An overdraft covers the gap for the few weeks until income recovers, and the interest on the amount used is deductible because the facility is for the trade.
- The repayment. As income picks up, the overdraft returns to zero, having done exactly its job, bridging timing, not funding a loss.
This is working-capital finance working as it should: a deductible, short-term bridge over a timing gap in an otherwise healthy practice. The overdraft comes back to zero, which is the signature of a facility used for timing rather than to mask a deeper problem.
The danger of funding losses with an overdraft
The flip side deserves a clear warning. An overdraft that is permanently at its limit, never returning to zero, is usually a sign that the practice is spending more than it earns, and borrowing to cover that gap just defers and deepens the problem while adding interest cost. Working-capital finance is for timing, not for funding ongoing losses. If you find the facility never comes back to zero, the issue is profitability, not cash flow, and it needs addressing at source, in the cost base or the income, as our guide to managing overhead costs covers. No amount of working-capital borrowing fixes a practice that does not make money; it only delays the reckoning. Distinguishing a timing gap from a profitability gap is the most important judgement an owner makes about working-capital finance.
Choosing and reviewing facilities
Finally, treat your working-capital arrangements as something to review, not set and forget. A practice's needs change as it grows, takes on debt, shifts its NHS and private mix, or alters its drawings, so a facility set up years ago may now be too small, too large, or more expensive than the current market offers. Reviewing the arrangements periodically, alongside the annual accounts and with your accountant, keeps them matched to the practice as it actually is. The right facilities, correctly sized, deductible, and used strictly for timing, let a profitable practice stay liquid through its lumpy outflows. The wrong ones, oversized, mispriced, or used to mask losses, add cost and hide problems. The difference comes down to understanding that working capital is a timing tool, and using it as nothing more. Our companion guide to the financial KPIs every owner should track includes the cash and debtor measures that tell you whether your working capital is healthy, and our guide to acquisition financing covers the longer-term borrowing that sits alongside these short-term facilities.