Agencies and professional services firms have a specific accounting problem: the thing you sell is time, and time does not arrive in the bank in the same shape it left the building. Work happens in one month, gets invoiced in another, and gets paid in a third, and the books have to hold all three at once without either flattering or understating the business.
Three things drive most of it. Revenue should follow delivery rather than invoicing, pass-through costs are not revenue, and utilisation is the number that predicts whether you make money.
Revenue follows the work, not the invoice
If you invoice a retainer upfront, that is not revenue yet. If you complete a phase of a project and invoice next month, the revenue belongs to the month you did the work. Both situations create a balance that carries between periods.
| Situation | What sits on the balance sheet |
|---|---|
| Invoiced upfront, work not yet done | Deferred revenue, a liability |
| Work done, not yet invoiced | Work in progress or unbilled revenue, an asset |
| Milestone billing on a long project | Both, at different points in the project |
| Retainer with unused hours | Depends on whether unused time rolls over or expires |
Firms that recognise revenue on invoicing get books that look lumpy and reward the wrong behaviour, since a heavy invoicing month reads as a great month regardless of whether the work behind it was profitable. It also makes month-to-month comparison meaningless, which is exactly what you need for pricing decisions.
Pass-through costs are not revenue
This one distorts more agency P&Ls than any other single item. If you buy $50,000 of media, contractor time or software on behalf of a client and rebill it, running that through revenue makes the firm look much larger and much less profitable than it is.
A firm doing $2 million of its own fee income plus $3 million of rebilled media is not a $5 million business with a 20% margin. It is a $2 million business with a 50% margin and a lot of cash moving through it. Those are completely different companies to run, price and value.
Whether you present pass-throughs gross or net turns on whether you control the service before it transfers to the client, which is a genuine judgment. What is not optional is tracking net fee income separately, because that is the number your margins, your pricing and your capacity planning should be built on.
Utilisation is the number that predicts profit
In a people business, the ratio of billable to available hours drives almost everything downstream. A firm can grow revenue while quietly becoming less profitable, and utilisation is where that shows up first.
- Utilisation: billable hours divided by available hours, per person and per team.
- Realisation: what you actually billed against what you could have billed at standard rates. This is where scope creep and write-offs become visible.
- Effective hourly rate: project fee divided by hours actually spent, which is the honest measure of whether a fixed-fee engagement worked.
- Project margin after all directly attributable time and cost, calculated per project rather than as a firm-wide average.
Effective hourly rate is the one most worth calculating retrospectively on fixed-fee work. It routinely reveals that the largest client is the least profitable, which is not a conclusion anyone reaches from the revenue number alone.
How to set it up
- Run accrual accounting, so revenue lands in the month the work happened.
- Track time against projects even on fixed-fee work, because without it you cannot compute effective rate or project margin.
- Separate net fee income from pass-through costs in the chart of accounts from the start.
- Maintain deferred revenue and unbilled work-in-progress schedules that reconcile to the ledger monthly.
- Report project margin and utilisation alongside the P&L, since the P&L alone will not tell you which work to sell more of.
Cash flow is a separate problem
Agency accounting can be entirely correct and the business can still run out of money, because payroll is weekly or monthly while client payment terms are thirty, sixty or ninety days. You are financing your clients, and the faster you grow the more you finance.
This is why a growing agency often feels tighter than a flat one. Winning a large client means paying the team to deliver months before the invoices clear. Track collections and days sales outstanding alongside the P&L, and treat a rising DSO as an early warning rather than an administrative annoyance. A 13-week cash flow forecast is the standard tool for exactly this shape of problem.
Project profitability, the report most agencies lack
Firm-level margin tells you whether the business worked last month. It does not tell you which clients paid for the others, and that is usually the more actionable question. Getting to it requires only that costs carry a project dimension, which is a chart of accounts decision rather than a software purchase.
The mechanics are straightforward. Every hour worked carries a cost rate, not a bill rate. Every pass-through cost is tagged to the project it belongs to. Every project then shows fee income, direct labour at cost, pass-through in and out, and a contribution margin.
| Line | Client A retainer | Client B project |
|---|---|---|
| Fee income | $40,000 | $40,000 |
| Direct labour at cost | $18,000 | $29,500 |
| Pass-through billed | $0 | $60,000 |
| Pass-through cost | $0 | $60,000 |
| Contribution | $22,000 | $10,500 |
| Contribution margin on fee | 55% | 26% |
Both clients look identical on revenue if pass-through is excluded, and Client B looks two and a half times larger if it is included. Neither reading is useful. The contribution line is, and it says Client A is roughly twice as valuable per fee dollar. Without the project dimension in the ledger, that conclusion is unavailable at any price.
The most common finding when a firm does this for the first time is that its largest client by revenue is not its most profitable, and is sometimes its least. That is a pricing conversation, a scoping conversation, or occasionally a resignation conversation, and none of them can start from firm-level numbers.
Utilisation, and how to make it honest
Utilisation is billable hours over available hours, and it predicts profit better than any other single operating number in a services firm. It is also the easiest number to quietly corrupt, in three ways worth naming.
- Counting hours that were worked but written off. If a project overruns and the excess is never billed, those hours are not billable regardless of what the timesheet says. Utilisation calculated before write-offs consistently overstates the health of the firm.
- Treating an inflated denominator as available. Available hours should net out holiday, training and genuine internal work. Using a flat 40-hour week produces a number that is always low and therefore always ignored.
- Averaging across seniority. A firm at 70% overall can be a partner at 30% and a junior at 95%, which is a very different business from an even 70% and usually a less durable one.
The link to the ledger is what makes the number trustworthy. If time is captured in one system and cost in another and nobody reconciles them, utilisation becomes an operational metric that never has to agree with the accounts. When labour cost by project comes out of the same place as the P&L, the two cannot drift.
Contractors, and the classification question
Agencies flex capacity with contractors, which is sensible and creates two obligations that are easy to miss.
The first is reporting. Payments to contractors above the reporting threshold require information returns, and the threshold for payments made after 31 December 2025 rose to $2,000 from $600. Collecting a W-9 at engagement rather than in January is the entire difficulty, and it is a process problem rather than an accounting one.
The second is classification, which carries more risk. Whether someone is a contractor or an employee is determined by the working relationship rather than the contract label, and getting it wrong creates exposure for back payroll taxes and penalties. A long-term contractor working your hours, on your systems, under your direction, is the pattern that attracts scrutiny. This is a question for your accountant and, where the facts are close, an employment lawyer, before the arrangement becomes established rather than after.
Where Zinance fits
Zinance runs books for professional services firms with the structure this requires: accrual revenue tied to delivery, pass-throughs separated from fee income, and margin reported per project rather than in aggregate. Books close daily, so a project going wrong is visible while you can still act on it. See our work with professional services firms.