How to Know Which Jobs Are Actually Making You Money

You're flat out. The diary is full, the vans are on the road, and turnover is up on last year. So why is there never any money in the bank, and why can't you say, hand on heart, which of your jobs actually made a profit?

It's one of the most common frustrations we hear from building contractors, and it has almost nothing to do with how hard you work. It comes down to a simple truth that's easy to lose sight of when you're busy: turnover is not profit. You can grow your revenue every year and still be going backwards on margin, and without job-level numbers, you won't see it happening until it's too late.

Here's how to get proper visibility of job profitability, so you can price with confidence, drop the work that's quietly costing you, and do more of what actually pays.

Why contractors lose sight of job profit

Construction is unusually good at hiding the true cost of a job. Unlike a shop that buys stock and sells it the same week, your costs and your income land at completely different times:

• Materials get bought on account and paid weeks later.
• Subcontractors invoice on their own schedule, with CIS deductions on top.
• Labour, plant hire and site costs trickle in across the whole job.
• You invoice in stages or on application, with retentions held back for months.
• Variations get done on a handshake and billed (if you remember) much later.

By the time everything has washed through, the job is long finished and you've already moved on to the next three. The profit, or the loss, disappears into one big bank balance, and the only number you can see is total turnover. That's why so many contractors are busy and stressed but no better off.

What "job costing" actually means

Job costing simply means assigning every cost to the job it belongs to, and comparing it against what you billed for that job. Done properly, it turns "we made money this year, I think" into "job 214 made 18%, job 219 lost 4%, and here's exactly why."

To do that, every cost needs a home. For each job you want to capture:

• Labour, including the real cost of your employed staff (wages plus employer's NIC, pension and holiday pay), not just the hourly rate.
• Materials, coded to the job, not lumped into one big "materials" pot.
• Subcontractors, gross cost before CIS deductions.
• Plant and equipment hire, and any site-specific costs (welfare, waste, access).
• A fair share of overheads, more on that below.

The four numbers to watch on every job

You don't need a finance degree to run a profitable site. You need four numbers, kept up to date:

1. Contract valueWhat you agreed to do the work for, including agreed variations. This is your ceiling.
2. Costs to dateEverything spent on the job so far, labour, materials, subbies, plant.
3. Amount invoiced / applied forWhat you've actually billed the client, so you can see if you're ahead of or behind your costs.
4. Estimated cost to completeAn honest view of what's left to spend. This is the number that turns a nasty surprise into an early warning.

Put those together and you get the two things that matter most: the real margin on the job, and your work in progress (WIP), the value of work you've done but not yet billed, or billed but not yet done. Get WIP wrong and your accounts will flatter you one month and punish you the next.

How to set it up without drowning in admin

The good news is you don't need a bespoke system. Most contractors we work with run this on cloud software they already have:

The key is discipline at the point of entry: if the lads are putting costs against the wrong job (or no job), the reports will be worthless. It's worth ten minutes getting your team into the habit.

The traps that quietly eat your margin

Forgetting overheads

Your office, vehicles, insurance, software and your own time all cost money before you've laid a single brick. If you only compare direct costs to the price, every job looks profitable while the business as a whole struggles. Build a sensible overhead recovery into your pricing so each job pays its share.

Unbilled variations

"Can you just also…" is where margin goes to die. Every variation you do and don't bill is pure loss. Track them as they happen and get them agreed in writing, it's the single easiest profit win on most sites.

Retentions you forget about

Money held back on completion is still your money. Left untracked, retentions tie up thousands and quietly hurt your cash flow. They should be on a list you actually chase.

What to do with the insight

Once you can see margin by job, the decisions get easier and a lot less emotional. You can re-price the type of work that consistently underperforms, walk away from clients who are more trouble than they're worth, and put your energy into the jobs and customers that reliably pay well. Over a year, small pricing corrections on repeat work add up to far more than chasing extra turnover.

The habit that makes it stick is monthly or quarterly management accounts: a short, regular look at how the business and its live jobs are performing, while there's still time to do something about it. Waiting until the year-end accounts land, six or nine months after the fact, is like checking the fuel gauge after the engine's cut out.

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