October 9, 2026 · Mitt Patel · 5 min read
You open the monthly statement from your supply house and it's four pages of wire, breakers and fixtures, none of it labeled by job. You know you bought it all. You have no idea which customer it belongs to, and the invoice is already due.
Why this happens
Most electricians run accounts at one or two supply houses. A tech grabs what he needs, the counter guy rings it up, and the invoice gets mailed or emailed to the office at the end of the month. Nobody asks which job the wire nuts were for, because the job is already done and everyone's moved on.
The result is a pile of material costs that sit in one general "supplies" bucket instead of landing on the jobs that used them. When that happens, your job costing can be unreliable. You think a job made money because you only counted labor and the quoted material estimate, not what actually got bought and used. You bid the next similar job the same way, using numbers that were wrong the first time.
It also makes disputes harder. If a customer questions a material charge, or you want to check whether a job ran over, you're stuck flipping through old invoices trying to remember which order was for which address.
A worked example
Say you run a supply house account and in one month you charge $4,000 across three jobs: a service panel upgrade, a kitchen remodel, and a small commercial tenant fit-out.
If none of the invoices are tagged, that $4,000 just shows up as "materials expense" for the month. You can't tell that the panel upgrade used $1,500 in gear, the kitchen used $1,800 in fixtures and wire, and the commercial job used $700 in conduit and boxes.
Now say the panel upgrade was quoted with $900 of material in the estimate. If you don't track that it actually used $1,200, you won't notice you're $300 light until you've bid three more panel upgrades the same way. Tag each invoice to the job, and you see the $300 gap right away. You can ask why, whether it was a pricing change at the supply house, extra gear the job needed, or something that should have been billed as a change order.
How to set it up
- Open a separate account at each supply house, in the business name. Don't let techs buy on personal cards and reimburse later. It breaks the paper trail and makes reconciliation harder.
- Require a job name or number on every purchase. Tell the counter staff at your regular supply houses to put the job reference on the ticket, not just "will call" or a tech's first name. Many counter staff will do this if you ask once and keep asking.
- Set up a job-tracking list. This can be as simple as a running list of active jobs with a short code for each one, so techs can call out "Job 114" at the counter instead of trying to explain the address.
- Record each invoice to its job as it comes in, not at month end. If you use QuickBooks Online, use the job or project feature to tag each material purchase to the right customer job, not just an expense category. This is what lets you pull a real cost report per job later.
- Reconcile the supply house account to its monthly statement. Match every line item on the statement to an invoice you've already recorded and tagged. Anything on the statement you can't match is a sign something slipped through untagged, or was billed to the wrong job.
- Flag returns and credits the same way. If gear gets returned, the credit needs to land back on the same job, or that job will look more expensive than it was.
Mistakes that undo it
- Letting "will call" purchases go untagged. These are the ones most likely to get bought under time pressure with no job reference, and they're also usually the most expensive single-item pickups.
- Reconciling by total instead of line by line. Checking that the statement total matches your books doesn't catch an invoice that got tagged to the wrong job. The totals can match while the job costs are still wrong.
- Mixing personal and business purchases on the same account. It happens when someone grabs a personal item at the counter and asks to put it on the business account "just this once." It complicates every reconciliation after that.
- Waiting until the invoice is overdue to record it. By then nobody remembers which job it was for, and you're guessing.
- Not tagging credits and returns. A returned reel of wire that never gets credited back to the job makes that job look like it cost more than it did.
Monthly checklist
- Every supply house invoice for the month is recorded with a job name or number.
- Each account statement has been reconciled line by line against recorded invoices.
- Any unmatched statement lines have been tracked down and tagged.
- Returns and credits are applied to the correct job.
- A quick job cost report has been pulled for any job that's finished, so actual material cost can be compared to what was quoted.
Common questions
What if a purchase covers materials for more than one job?
Split it. Record the invoice in two or more lines, each tagged to its own job, using the actual amounts from the ticket if the supply house itemizes it that way. If it doesn't itemize, use a reasonable estimate based on what you know you bought for each job, and note how you split it so you can be consistent next time.
Do I need to do this for small cash purchases too?
Yes, if the amounts matter to your job costing. A ten-dollar box of wire nuts probably doesn't move the needle, but if techs are regularly picking up fifty or a hundred dollars in parts on a job, those add up across a year and should get tagged the same way as the account purchases.
What if the supply house won't put job names on the invoice?
Ask once, clearly, since it's a small request many supply houses are willing to accommodate. If they won't, keep your own log: write the job reference on your copy of the invoice before you file it, and record it tagged to that job in your own books even if the supply house's paperwork doesn't show it.
How far back should I go to clean up untagged invoices?
Start with the current month and get that reconciled cleanly. Then work backward as time allows, prioritizing any job that's still open or any job you're using as a reference for a current bid.
North Hudson Bookkeeping sets up supply house tracking like this for electricians across North Jersey, and helps keep it reconciled every month so your job costs stay easier to track without you having to chase paperwork. The first call is free if you want to see what it would take to get your accounts in order.
