TL;DR
- 30-50%
- 10-20%
- Monthly
- <20%
💡Quick reference summary. Continue reading for comprehensive analysis and context.
Most agency founders can tell you their total revenue, their biggest client, and roughly what they paid themselves last year. Far fewer can tell you which clients actually make them money and which ones are quietly draining it.
Revenue is not profit. A £10,000-per-month client who demands constant revisions, ties up your senior team, and pays 60 days late may be less profitable than a £4,000-per-month retainer that runs smoothly with junior staff. Until you measure it, you are guessing.
This guide walks through exactly how to calculate per-client profitability, what to do with the results, and how to build it into your monthly rhythm so you never have to guess again.
Why revenue per client is misleading
Revenue tells you how much money came in. It says nothing about what it cost to earn it. Two clients paying you £8,000 per month can have wildly different profitability:
Client A: £8,000/month
- Managed by one mid-level account manager
- Clear briefs, minimal revisions
- Pays within 14 days
- Team cost: £3,200/month
- Margin: 60%
Client B: £8,000/month
- Requires senior strategist on every call
- 3-4 revision rounds per deliverable
- Pays at 45-60 days
- Team cost: £6,800/month
- Margin: 15%
Same revenue. Completely different contribution to the business. If you only look at revenue, Client B looks just as valuable as Client A. In reality, Client B is barely covering its costs and consuming capacity that could serve a more profitable client.
The client profitability formula
Client Profit = Client Revenue − Direct Costs − Allocated Overhead
Each component needs to be calculated properly. Here is what goes into each one.
Direct costs
Direct costs are everything you spend specifically to service that client. The biggest one is team time.
| Cost type | How to calculate | Example |
|---|---|---|
| Team time | (Annual salary + NI + pension) ÷ productive hours × hours on client | £45k salary = ~£32/hr cost rate |
| Subcontractors | Invoiced cost for freelancers/contractors on this client | £2,000/month for freelance developer |
| Client-specific tools | Software licenses, stock imagery, platform fees used only for this client | £200/month for analytics platform |
| Media spend | Pass-through at cost (unless you mark it up) | £5,000/month ad spend (pass-through) |
Calculating your cost rate
Take each team member's annual salary, add employer NI (13.8% above the secondary threshold) and pension contributions (typically 3-5%). Divide by productive hours per year (roughly 1,650 after holidays, sick days, and non-billable time). A £45,000 salary typically works out to around £32 per hour at cost. A £65,000 salary is closer to £46 per hour.
Allocated overhead
Overhead is everything you pay regardless of which clients you serve: office rent, utilities, admin staff, accounting software, insurance, your own management time. It needs to be shared across clients somehow.
Two methods work well for agencies:
Method A: Per-head allocation
Divide total monthly overhead by headcount. Allocate to each client based on the proportion of team hours they consume.
Best for: service agencies where team time is the primary cost driver.
Method B: Revenue-based allocation
Express overhead as a percentage of total revenue. Apply that percentage to each client's revenue.
Best for: agencies with significant non-labour costs (media spend, licensing).
Either method is better than ignoring overhead entirely. Most agencies find that overhead represents 25-40% of revenue. If you are not allocating it to clients, you are overstating every client's profitability by that amount.
Worked example: a 10-person agency
Take a digital marketing agency with 10 staff, £80,000 monthly revenue, and £20,000 monthly overhead (rent, admin, software, insurance). Here is how client profitability might look across four clients:
| Client | Revenue | Direct costs | Overhead | Profit | Margin |
|---|---|---|---|---|---|
| Acme Digital | £25,000 | £10,000 | £6,250 | £8,750 | 35% |
| Bright Media | £30,000 | £14,000 | £7,500 | £8,500 | 28% |
| Crest Properties | £15,000 | £11,500 | £3,750 | -£250 | -2% |
| Delta Group | £10,000 | £4,500 | £2,500 | £3,000 | 30% |
Crest Properties is the third-largest client by revenue but the only one losing money. Without this analysis, you might assume they are a valuable client because they pay £15,000 per month. In reality, you would be better off without them, since the capacity they consume could serve a profitable client instead.
The scope creep tax
Scope creep is the single biggest hidden cost in most agencies. It is work you deliver but never invoice for, because it falls in the grey area between “included” and “extra”.
The maths of scope creep
A £50,000 annual client with 10% scope creep = £5,000 of unbilled work
Do that across 10 clients = £50,000 per year in lost revenue
At 20% scope creep (not unusual) = £100,000 per year
That is revenue you earned but never collected. It comes straight off your bottom line.
Scope creep happens incrementally. An extra revision here, a quick favour there, a “small” additional request that takes two hours. None of them feel worth raising individually, but they compound.
The fix is tracking budgeted hours versus actual hours at the project level. When a project hits 75-80% of its budgeted hours, flag it. That is the moment to have a conversation with the client about remaining scope or a change order, not after the project is finished and the time has already been spent.
Red flags for unprofitable clients
You do not always need a full P&L to spot trouble. These patterns usually indicate a client is unprofitable or heading that way:
Excessive revision cycles
More than 2 rounds of revisions per deliverable, consistently. Each round costs hours that were not in the scope.
Response-time demands outside SLA
Expecting same-day turnarounds on non-urgent requests, or calling outside working hours. This disrupts team workflow and increases context-switching costs.
Slow payment
Consistently paying beyond 30 days. Late payment has a real cash flow cost: you are funding their work while waiting to be paid.
High account management ratio
If your account manager is spending 40% of their time on a client that represents 15% of revenue, the ratios are wrong.
Scope ambiguity in contracts
Vague deliverables lead to disagreements about what is included. The client thinks it is included; you think it is extra. You usually lose that argument.
Senior staff on junior tasks
If your most expensive people are doing work that a mid-level team member could handle, the cost rate is wrong for the task.
When to renegotiate vs when to fire a client
Not every unprofitable client should be dropped. Some are worth fixing. The question is whether the problem is structural or behavioural. A client with low short-term profitability but high client lifetime value — through referrals, case study potential, or growing budgets — may justify the investment. But you need the data to make that call.
Renegotiate when:
- The client is strategically valuable (reference, sector credibility, growth potential)
- The margin problem is fixable through pricing (fees are simply too low for the scope)
- Scope creep is the issue and clearer contracts would fix it
- The relationship is good and the client would be receptive to a conversation about value
Fire when:
- The account is margin-negative after honest cost allocation and has been for 3+ months
- The client is damaging team morale or causing staff turnover
- Scope creep is escalating despite previous renegotiation attempts
- Payment terms are repeatedly ignored
- The client consumes disproportionate management time
Before you fire a client
Always check your contract notice period and any minimum term. Have a plan for how you will reallocate the freed-up capacity. And be professional: a clean exit protects your reputation. The agency world is small.
Building profitability tracking into your workflow
Client profitability analysis only works if it is a regular habit, not a quarterly surprise. Here is what a practical rhythm looks like:
Weekly: time tracking review
Check that all team members have logged their time against the correct clients and projects. Flag any project that has hit 75% of budgeted hours. This takes 15 minutes and catches scope creep before it accumulates.
Monthly: client P&L
Run a per-client profit and loss report. Revenue, direct costs, allocated overhead, margin. Flag any client below your threshold (30% is a reasonable starting point). Review the flagged clients and decide: investigate, renegotiate, or plan an exit.
Quarterly: portfolio review
Look at the full client portfolio. Rank clients by margin. Identify trends: is a previously profitable client declining? Is a new client performing better than expected? Use this to inform business development priorities and resource allocation.
Tools for tracking client profitability
You need two things: accurate time data and a way to turn it into financial reports. Here are the tools that work well for UK agencies:
| Tool | Best for | Pricing |
|---|---|---|
| Xero Projects | Agencies already on Xero. Combines time tracking with invoicing and cost rates in one place. | Included in Xero Premium |
| Harvest | Simple time tracking with built-in project budgets and reporting. Integrates with Xero and QuickBooks. | From £9/user/month |
| Toggl Track | Easy adoption. Good for teams resistant to time tracking. Simple interface, strong reporting. | Free tier available |
| Float | Resource planning plus profitability. Shows who is allocated where and at what cost. | From £6/person/month |
For most agencies, a time tracker (Harvest or Toggl) connected to your accounting software (Xero or QuickBooks) gives you everything you need for a monthly client P&L. You do not need enterprise software. You need consistent time tracking and 30 minutes a month to run the numbers.
Getting started: your first client profitability review
If you have never done this before, start simple. Pull the last three months of data and work through these steps:
List your clients and their monthly revenue for the last quarter.
Pull time data for each client. If you do not have time tracking, estimate hours based on team allocation. Then start tracking properly from this month.
Calculate cost rates for each team member. Annual employment cost divided by productive hours (roughly 1,650).
Calculate direct costs per client: team hours multiplied by cost rates, plus subcontractors and client-specific tools.
Allocate overhead using the per-head or revenue-based method.
Calculate margin for each client. Rank them. Identify your top 3 and your bottom 3.
The first time you do this, the numbers will surprise you. That is the point. Once you can see the real picture, you can make informed decisions about pricing, capacity, and which clients to invest in.
Frequently asked questions
How do you calculate client profitability in an agency?
Client profitability equals client revenue minus direct costs (team time at cost rate, subcontractors, client-specific software) minus an allocated share of overhead (rent, admin, management time). The result is the actual profit each client generates. A positive margin above 30% is healthy for most agencies.
What is a good profit margin per client for an agency?
A healthy per-client margin for UK agencies is 30-50% after direct costs and allocated overhead. Below 20% should trigger a review. Below 10% means you are likely losing money once all costs are properly accounted for.
How much does scope creep cost agencies?
Scope creep typically costs agencies 10-20% of project revenue in unbilled time. On a £50,000 annual client, 10% scope creep equals £5,000 of work delivered but never invoiced. Across ten clients, that is £50,000 per year in lost revenue.
When should an agency fire a client?
Fire a client when: the account is consistently margin-negative after honest cost allocation, the client is damaging team morale or causing staff turnover, scope creep is escalating despite renegotiation attempts, or payment terms are repeatedly ignored.
How do you allocate overhead to clients in an agency?
Two methods work well. Per-head allocation divides total overhead by headcount and allocates based on hours consumed. Revenue-based allocation applies overhead as a percentage of each client's revenue. Per-head is more accurate for service agencies.
What are the red flags for unprofitable agency clients?
Key red flags include excessive revision cycles, frequent out-of-hours requests, slow payment beyond 30 days, high account management ratio relative to revenue, and scope ambiguity in contracts.
How often should agencies review client profitability?
Monthly at a minimum. Run a per-client P&L each month. Flag any client below your threshold (typically 30% margin). Weekly time tracking reviews help catch scope creep before it accumulates.
What tools help agencies track client profitability?
Xero Projects for agencies on Xero, Harvest or Toggl for time tracking, Float for resource planning. Most agencies need a time tracker plus their accounting software for monthly client P&L reports.