The year ends. Revenue is up. The business has grown by close to a fifth. The founder expects profit to have followed. It hasn’t, or not by enough to make the effort feel worth it. The number goes up, the reward doesn’t. That gap has a name, and it usually has two overlapping causes.
What are margin leakage and overhead creep?
Margin leakage is the gradual erosion of profit that happens not because revenue falls but because delivery costs, discounts, rework or unbilled extras consume a growing share of what comes in. Overhead creep is the parallel problem: fixed and semi-fixed costs rising incrementally until they take a larger cut of revenue than they used to. Both tend to compound quietly, often for months before they show up in the annual figures.
The distinction matters because each demands a different fix. Leakage lives in how individual jobs are priced, scoped and delivered. Creep lives in the firm’s recurring cost base. A business can have both at once. One might be driving the problem more than the other, or they might be contributing in roughly equal measure. Treating them as the same issue leads to the wrong intervention.
Why does growth make them harder to see?
When revenue is rising, the instinct is to read it as health. A busier firm looks like a successful firm. That instinct is what makes growth a poor early-warning system. Turnover can rise while gross margin per job quietly narrows, delivery complexity increases, and overheads added to support growth start to erode the gains. The headline numbers move in the right direction; what they conceal surfaces later.
Convex Accounting describes the dynamic plainly: a business can look healthy because it is busy and revenue is growing, even while job profitability and labour recovery are deteriorating underneath. The busy-ness provides cover. A founder who is heads-down on delivery rarely has the reporting infrastructure to see what is happening at job or client level until the year-end accounts deliver the surprise.
The problem compounds during growth phases because growth usually means more complexity. More clients, more service variants, more staff, more subcontracting. Each addition brings new cost and new opportunity for things to drift out of alignment with pricing.
The founder who checks company-wide gross margin monthly and sees it holding steady may not notice that two high-complexity clients are being cross-subsidised by three straightforward ones. Company-level figures aggregate the good and the bad. The problem stays invisible until the profitable work churns or the complex work grows to dominate the book.
Where will you actually meet them in a service firm?
In a service business, margin leakage shows up in a handful of recognisable places. Scope creep on project work, where extra effort is delivered but never re-priced. Pricing that hasn’t kept pace with labour or supplier costs. Billing delays or write-offs absorbed as part of normal delivery. Overhead creep arrives separately, through software subscriptions added one at a time, higher insurance premiums at renewal, and admin functions expanding alongside headcount.
Enterprise Times identifies missed billing, poor estimating and the absence of a clear budget-versus-actuals view as the main structural causes in professional services firms. Marco Broin’s analysis of overhead creep in owner-managed businesses points specifically to the incremental additions: extra tool seats, expanded admin capacity, management layers added to support growth. Each looks sensible at the time. The cumulative effect is what erodes contribution margin.
Concession discounting is a further leakage vector. A client pushes back on price. The founder wants to close or retain the relationship. The discount makes sense in the moment, but it sets a reference point that proves difficult to raise. Over time, the concession becomes the expected price, and the margin on that client deteriorates permanently.
A firm that adds three new clients and two members of staff in the same quarter may have grown revenue while making each existing client relationship slightly less profitable. The growth is real. The margin erosion running alongside it is also real.
When should you act on it, and when is it not the issue?
The signal worth acting on is a widening gap between revenue growth and profit growth. If turnover is rising but net profit is flat or narrowing, that gap deserves investigation at job and client level. If profit is growing alongside revenue, leakage is probably not the dominant issue. The error is to assume rising revenue means a healthy business, and never check what that growth is actually costing.
There are situations where lower short-term margin is expected and acceptable. A deliberate investment phase, where the business is building capacity ahead of demand, narrows margin temporarily by design. Fixed-price contracts with tight change control limit the impact of scope creep. A firm growing primarily through volume on a repeatable, standardised service faces a different risk profile from a bespoke professional services business adding complexity with each new client.
A lower margin matters less than whether the founder knows why it is lower, and whether the drop reflects a conscious decision or a slow drift nobody noticed. One is strategy. The other is a problem waiting to become visible.
What to check before your next planning round
The most useful starting point is gross margin by client, job or service line, not aggregate turnover or net profit alone. A company-level gross margin figure can look acceptable while hiding one or two relationships that are deeply unprofitable. Looking at the components tells you whether the growth is worth having and where the operational work needs to go before the next planning cycle.
Convex Accounting recommends monthly financial review rather than waiting for year end. That cadence matters because leakage and creep are gradual processes. A monthly review of job margin, write-offs, discounting and labour recovery gives early warning. A year-end review gives an explanation of something that has already cost the business. The gap between those two positions is significant.
The overhead audit is a separate exercise. Go through every recurring commitment and ask whether the spend is still earning its keep. Software subscriptions are the obvious starting point. Many owner-managed businesses have accumulated tools added during a period of growth and never reviewed when that growth plateaued. Seat counts, licence tiers and tools with overlapping functions are all worth examining.
On pricing: any growth plan that does not include a review of whether prices have kept pace with input costs is incomplete. Labour costs, supplier prices and energy costs move. If client prices do not, the business absorbs the difference from margin. NetSuite and Convex both identify underpricing relative to input cost growth as a direct driver of margin erosion, not a background risk.
Cutting overheads that are genuinely delivering value slows the business. The exercise is one of visibility, asking which parts of the operation are profitable, which are not, and whether the unprofitable parts are temporary, fixable or structural. That distinction determines what you do next, and it only becomes clear when you measure at the right level of detail.
