How do I know if we’re actually making a profit on each job? (Direct answer)
You know you’re making a profit on each job when you can compare budget vs actual costs in real time, allocate every cost to the correct project using cost codes, and reconcile this with Work in Progress (WIP) so your reported profit matches what’s actually been earned — not just what’s been invoiced. If your numbers rely on gut feel or bank balance, you’re guessing.
Why is it so hard to know profit per job in construction?
Because construction is not like retail or a service business where the sale and the cost happen neatly together.
In construction, you can:
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buy materials in bulk for several jobs
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pay subcontractors weeks after they worked
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invoice in stages (and sometimes late)
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have variations that aren’t agreed (or billed) yet
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use labour across multiple sites
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start a job in March and finish in September
That makes profit easy to distort unless you track it properly.
At Thomas Emlyn Ltd, we often meet strong builders running great projects — but their finances lag behind reality. The common theme is this:
“We’re busy, we’ve got money in the bank… but I’ve no idea which jobs are actually making us money.”
What is “job costing” and why does it matter?
Job costing is the process of tracking all costs and income against each job so you can see exactly what’s profitable — and what isn’t.
It matters because:
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Turnover doesn’t equal profit.
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Cash in the bank isn’t margin.
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You can be “busy” and still go backwards financially.
A business that knows its job profitability can:
✅ price more confidently
✅ spot overruns early
✅ negotiate variations quickly
✅ stop repeat mistakes
✅ improve cashflow and margins
And that’s the core mission of Thomas Emlyn Ltd:
Stronger margins, healthier cashflow, and sustainable growth.
How to know if you’re making profit on each job (the 5 signals)
Here are the 5 clear signs your business has job-level profitability under control:
1) You have a budget for every job (before you start)
If you don’t know what the job should cost, you’ll never know if it’s on track.
A simple job budget includes:
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labour (direct + supervision)
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subcontractors
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materials
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plant hire
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prelims (site setup, welfare, skips, etc.)
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overhead contribution
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expected profit margin
Rule of thumb:
If you’re not budgeting each job, you’re not managing profitability — you’re just hoping.
2) Every cost hits the right job (not just the right supplier)
This is the #1 reason job profit reports are wrong.
If your bookkeeping is too vague (e.g. “Materials – £18,000”), you can’t see job-level truth.
You need:
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job tracking turned on in your accounting system (Xero, Sage, QuickBooks etc.)
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consistent job naming
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cost codes (more on this below)
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clean processes for purchase invoices and cards
3) You track costs weekly (not after the job finishes)
Waiting until the job ends is like checking the scoreboard after the final whistle.
A good construction firm checks:
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budget vs actual costs
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labour hours vs allowance
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subcontractor spend vs progress
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materials vs stage completion
every week.
At Thomas Emlyn Ltd, our Virtual Finance Office (VFO) service often introduces a simple weekly rhythm:
Monday/Tuesday: bookkeeping up to date
Wednesday: job costing snapshot + WIP review
Thursday: margin & cashflow actions
Friday: director summary (what needs attention next week)
4) Your WIP matches reality (so profits aren’t “phantom profit”)
Work in Progress (WIP) is one of the most misunderstood numbers in construction — but it’s critical.
WIP answers this question:
“How much profit have we actually earned so far on jobs that aren’t finished yet?”
Without WIP:
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your accounts can show huge profit one month and a loss the next
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invoicing timing distorts performance
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you might take dividends based on imaginary profit
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you can underpay tax and get caught later
A proper WIP calculation is built from:
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contract value
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stage completion
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costs incurred
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estimated costs to complete
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invoices issued
If you’re UK-based, WIP is also tied to how you recognise revenue under accounting rules (most firms apply FRS 102 / UK GAAP principles in practice, even if they’ve never called it that).
5) You can name your most profitable job — and your worst
This sounds simple, but it’s powerful.
If I asked you:
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“Which job made the best margin in the last 90 days?”
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“Which job is quietly bleeding cash?”
…and you can’t answer confidently, job costing isn’t working yet.
What are cost codes (and do you really need them)?
A cost code is just a category that makes job costs meaningful.
Instead of seeing:
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“Job A – £120,000 cost”
You see:
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labour – £28,000
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subcontractors – £52,000
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materials – £31,500
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plant – £4,250
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prelims – £4,250
This helps you spot where you’re leaking margin.
Example cost code list (simple but effective):
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Labour
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Subcontractors
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Materials
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Plant & Hire
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Prelims / Site Setup
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Variations
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Overheads allocation (optional)
At Thomas Emlyn Ltd, we help firms implement cost codes in a way that’s actually usable — not overcomplicated.
A real-world example: the “profitable” job that wasn’t
(Anonymised, based on a typical scenario we see regularly.)
A building contractor had a £180,000 job. On paper it looked healthy:
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invoiced: £160,000 so far
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costs recorded: £120,000
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“profit”: £40,000 (25% margin)
But once we fixed the job costing:
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£18,000 of subcontractor costs were coded to “general”
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£9,500 of materials were sitting in “stock” / uncategorised
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labour was under-allocated by £7,800
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variations weren’t recorded or billed (£14,000 outstanding)
The real picture:
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true costs to date: £155,300
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true profit to date: £4,700
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and they were heading for a loss unless they acted immediately
Because we caught it mid-job, they:
✅ raised variation claims within 7 days
✅ renegotiated subcontractor scope
✅ corrected labour allocation
✅ recovered margin and finished at ~8% profit instead of a loss
That’s the difference between “accounts” and management information.
How to set up job profitability tracking (practical step-by-step)
Here’s the approach we typically implement inside a Virtual Finance Office (VFO) at Thomas Emlyn Ltd:
Step 1: Choose your tracking method
Options:
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accounting software tracking categories (e.g. Xero Tracking)
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job costing add-ons (depending on system)
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project management tools linked to accounting
Don’t start with fancy tools. Start with consistency.
Step 2: Create job setup rules (so your team can’t break it)
Define:
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how jobs are named
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who sets them up
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what codes are used
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where costs must be allocated
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what happens if something isn’t allocated
The goal is: no cost without a job.
Step 3: Track labour properly (most firms don’t)
Labour is the biggest hidden margin killer.
You need:
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timesheets linked to jobs
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labour cost allocation (even if payroll isn’t job-tracked automatically)
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separation of chargeable vs non-chargeable time
Even a basic weekly spreadsheet is better than nothing — as long as it’s consistent.
Step 4: Do a weekly job costing review
A simple weekly review checks:
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job margin % vs target
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over/underspend by cost code
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variations logged vs billed
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subcontractor commitments
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cashflow impact in the next 2–4 weeks
This is where profit becomes controllable.
Step 5: Add WIP monthly (minimum)
Weekly job costing.
Monthly WIP.
This keeps your accounts aligned with reality — and prevents “phantom profit.”
What is a “good” profit margin in UK construction?
There’s no single answer — but many UK construction SMEs operate on surprisingly tight net margins.
As a rough guide:
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Gross margin might sit anywhere from 15% to 35% depending on trade and model
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Net profit can often be 3% to 10% for well-run SMEs
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specialist subcontractors may achieve higher if systems are tight
The key isn’t comparing yourself to a generic benchmark.
It’s knowing:
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your target margin per job
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your actual margin per job
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what drives the gap
That’s what Thomas Emlyn Ltd helps you build.
Why “cashflow” can look good even when you’re losing money
A warning sign we see often:
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You win a big job
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You invoice a deposit or stage payment
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Cash comes in
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It feels like profit
But the true costs hit later — especially subcontractors and snagging.
That’s why construction cashflow management must be connected to job profitability and WIP.
If not, the business can drift into trouble while still looking “busy.”
How Thomas Emlyn Ltd helps construction firms get clarity (and control)
Most firms don’t need more reports.
They need:
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clean bookkeeping
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job costing that reflects reality
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a weekly financial rhythm
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margin control systems
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WIP that prevents nasty surprises
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director-level insight without admin overload
This is exactly what our Virtual Finance Office (VFO) and Virtual Finance Director (VFD) services are built for.
If you want to:
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know profit per job
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protect margin
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improve cashflow predictability
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and make decisions with confidence
…we can help.
Authority building: where you’ll see Thomas Emlyn Ltd
We’re committed to becoming a trusted voice in UK construction finance — not just for our clients, but the industry.
You’ll increasingly see Thomas Emlyn Ltd:
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featured on construction business podcasts
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contributing insights to industry articles and trade publications
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partnering with software providers and construction networks
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delivering workshops on job costing, WIP and margin improvement
If you host a podcast or run a construction community, we’re open to collaborations that genuinely help business owners.
FAQ: Job profitability in construction (UK)
1) How often should I review job profitability?
Weekly is ideal. Monthly is the minimum. Weekly reviews catch overruns early, when you can still take action. Monthly reviews are often too late — you’re looking at history, not control.
2) Do I need job costing software or can I do it in Xero/Sage?
Many firms can start with Xero/Sage using tracking categories plus a simple job costing structure. Software add-ons can help later, but the biggest improvement usually comes from process and discipline — not tools.
3) What’s the difference between profit and cashflow on a job?
Profit measures whether the job makes money overall. Cashflow measures timing — when money comes in vs when it goes out. You can be profitable but broke, or cash-rich temporarily while actually losing money. You need both.
4) Why does my accountant say I made profit, but I feel like I didn’t?
Because accounts often follow invoicing and timing, while construction reality follows progress and costs. Without WIP and accurate job costing, the profit figure can be misleading. That’s why management accounts matter.
5) What’s the biggest mistake firms make with job profitability?
Not allocating costs properly — especially labour and subcontractors. The second biggest mistake is ignoring variations until it’s too late. Both destroy margins quietly.
Want clarity on your job profitability?
If you’d like Thomas Emlyn Ltd to review your job costing system, WIP approach, and margin reporting, we can show you exactly what’s working, what’s missing, and how to fix it — without drowning you in admin.
Thomas Emlyn Ltd
Stronger Margins – Healthier Cashflow – Sustainable Growth
