Job Costing for Electricians: How to Know What Each Job Actually Made You
Most electricians know their day rate, know their materials markup, and still end a job not entirely sure whether they made good money or just broke even.
That gap between knowing your rates and knowing your actual profit is what job costing solves. This article explains how job costing works for electricians, why the standard approaches fall short, and what a practical tracking system looks like in the context of real electrical work.
Why Electricians Have a Specific Job Costing Problem
The job costing challenge in electrical work is different from a simpler trades scenario because the cost structure has more moving parts.
A plumber replacing a boiler has a clear scope: the boiler, the fittings, the labour. An electrician rewiring a semi-detached house faces cable runs priced by the metre, a CU that changes spec mid-job, additional circuits the customer asks for on day two, test equipment time, and small consumables from the van that never get invoiced separately.
The result is a common pattern on r/electricians: "I'll know I billed 1,800, but between materials, my time, my mate's time, and bits I pulled from the van, I have no idea if I netted 900 or 200."
That quote is not unusual. It describes a job costing failure, not a pricing failure. The rate was probably right. The capture of actual costs was not.
What Job Costing Actually Means
Job costing is a simple concept: for each job, record what it earned and what it cost, so you can calculate the actual profit for that specific job.
Not profit for the month. Not total invoices minus total supplier spend. Profit for this rewire, this consumer unit change, this EV charger installation.
The reason per-job visibility matters is that your electrical work is not homogeneous. A straight CU swap is high margin, quick to complete, low material cost. A full rewire on a difficult property with limited access, awkward cable routes, and a fussy client can cost more than estimated. Averaging these together into a monthly P&L hides the pattern.
When you track per-job, you start to see which job types make you money and which ones look profitable on paper but are not in practice. That information changes how you quote. It changes which jobs you chase. Over a year, it changes your income.
The Problem with How Most Electricians Track Costs
Most self-employed electricians use one or more of three approaches, and all three have the same flaw.
Mental accounting. You remember roughly what you spent. This works for simple jobs and fails on anything that runs longer than a week or involves multiple supplier runs.
Bank statement review. At month end (or year end), you go through transactions and try to assign them to jobs. This is archaeology: you are trying to reconstruct which payment went to which job after the fact. Some purchases do not match to a single job. Van stock complicates everything.
Accounting software. QuickBooks, Xero, and FreeAgent will show you materials as an expense category. They will not show you which job those materials belong to unless you manually enter and tag every transaction, which almost nobody does consistently.
All three approaches share the same structural flaw: the cost capture does not happen at the point of purchase. It happens later, from a desk, from memory. By then, the precision is gone.
What Good Job Costing Looks Like for an Electrician
The principle that makes job costing work is simple: capture the cost at the moment it happens, and attach it to the job in the same action.
That means when you leave a wholesaler with a bag of cable and a box of back boxes, the receipt is captured before you start the van. Not tonight. Not at the weekend. Now.
Here is what a practical job costing workflow looks like for an electrical sole trader:
Step one: a job exists in your system before work starts. The job has a name, an address, and a quoted price. It does not need to be elaborate.
Step two: every supply house run ends with a receipt scan. You take the receipt, point the camera at it, it reads the total and the items, and it goes into the right job. This takes under a minute in the car park.
Step three: the job shows a running profit figure. As receipts come in, the system subtracts them from the billed amount. You can see at any point what the job is running at: are you on track, over budget, or ahead?
Step four: when the job is complete, the final figure is accurate. You did not reconstruct anything. Every purchase was captured live. The profit number is real.
The Specific Costs Electricians Need to Track
Not all trade businesses have the same cost mix. For electricians, the categories that matter are:
Materials (high volume, high variability). Cable, accessories, CUs, containment, fixings. These vary enormously between jobs and between wholesalers. Capturing them per job is the core of electrical job costing.
Van stock used (harder to track, but worth noting). If you pull 20 metres of 2.5mm twin and earth from van stock that you bought three weeks ago, that cost belongs to this job even though the receipt is old. A practical approach is to note van stock use in the job record as a rough value, without receipt-scanning old purchases. Precision matters less than consistency.
Subcontractor or labourer costs. If another electrician or a mate works with you on a job, their cost (day rate or invoice) belongs to that job. Log it the same way you log a materials receipt.
Specialist equipment hire. If you hire a hydraulic cable puller or a SDS drill for a specific job, that cost is job-specific and should be tracked.
What you do not need to track per job (usually). Your white van, your test equipment, your insurance, your NIC membership, your accountancy fees. These are overhead, and they belong in your general business accounting, not your per-job records.
How This Changes Quoting Over Time
Once you have six months of per-job data, you can answer questions you currently cannot answer:
"My domestic rewire jobs: what do they actually cost me in materials, on average?"
"Which job types have the best margin? CU changes? EV chargers? Commercial installs?"
"Is there a job size or duration where my margins start to compress?"
These answers let you refine your quoting not by guessing but by reference to your own historical data. That is a durable advantage that builds over time.
UK Sole Traders: HMRC, CIS, and Self Assessment
For UK electricians working as sole traders, job costing and tax accounting are two separate things.
Your Self Assessment return categorises your income and expenses by type: materials, subcontractors, motor expenses, and so on. It does not care which job a materials purchase belongs to. HMRC wants totals by category, not by job.
Job costing is a business management tool, not a tax compliance tool. The two live separately and complement each other: your accountant uses the totals, you use the per-job numbers.
If you work under CIS as a subcontractor, the same applies. CIS deductions are tracked at the income level. Your per-job costs still need to be tracked separately if you want to know what each contract actually made you.
Self Assessment deadline for UK sole traders is 31 January following the tax year end. See the government's self-employment pages for current rates and filing requirements. (Volumes for "self assessment deadline" are UNVERIFIED in DataForSEO but this is a high-frequency question from the target audience based on r/electricians traffic patterns.)
What VanReceipts Does for Electrical Job Costing
VanReceipts is an iPhone app built for exactly this workflow. It uses Apple's Vision framework to read receipt text on your phone by default. Optional cloud AI itemization for tough receipts is off unless you turn it on. The time and place of the scan suggest which job you are on, so the receipt is matched with one tap to confirm.
What you see is live job profit: billed amount, materials, mileage, labour, and current net. Every receipt, trip, and hour updates that number in real time.
For an electrician, the workflow is:
- Leave the wholesaler.
- Open VanReceipts.
- Scan the receipt.
- Done. Back to the job.
Live job profit shows where each job stands without any desk work. At the end of the job, the number is accurate because it was built receipt by receipt, not reconstructed from memory.
VanReceipts does not generate CIS statements, help with VAT returns, or replace full accounting software. It handles the job money loop your accounting software leaves out: estimates, invoices, receipt costs, mileage, and live per-job profit from the field.
Starting Today
You do not need a new system on every job at once. Start with your next job. Set it up, scan every receipt from that job, and see what the final profit figure looks like versus what you expected.
That one comparison will tell you whether your gut estimate of margins is accurate or whether you are leaving money unaccounted for on every job.
VanReceipts is free to start (10 receipt scans per week on device). Pro adds unlimited scans, cloud itemization, crew labour, full profit history, and iCloud sync, with a 7-day free trial.
*VanReceipts (App Store name: Easy Invoices & Expenses) is an iPhone app for tradespeople: estimates, invoices, mileage, receipt expenses, and per-job profit. Receipts are read on your phone by default. Optional cloud AI itemization is off unless you turn it on. Free includes 10 scans per week. Pro is $14.99 per month or $99.99 per year, with a 7-day free trial.*