October 28, 2026 · Mitt Patel · 6 min read
You close out 42 repair orders this month, each one carrying a $6 shop supplies charge. That's $252 you billed customers for rags, fluids, and hardware. You never actually counted what you spent on those things, so you have no idea if $252 covered it, fell short, or left money on the table.
Why the mismatch happens
Shop supplies charges on repair orders are often a flat fee or a small percentage of labor, and many shops set the number once and rarely revisit it. They're meant to cover the small stuff you don't invoice line by line: shop rags, degreaser, zip ties, small fasteners, blue tape, disposable gloves. The fee is a guess, and it's rarely revisited.
What you actually spend on those items moves with the type of work you're doing, how many cars come through, and what your suppliers charge that month. A month heavy on brake jobs eats more parts cleaner and fasteners than a month of oil changes. A supplier price increase on gloves or rags doesn't automatically bump your flat fee.
Many shops never compare the two numbers because they land in the same place on the books. The shop supplies charge gets buried in repair order income, and the shop supplies cost gets buried in general shop expenses or lumped in with parts purchases. Nobody sees them side by side, so nobody notices when the fee has drifted away from the real cost.
The cost of not knowing shows up in small decisions that can add up over time. You might keep a flat fee that's been too low for two years, quietly eating into every job's margin. Or you might think shop supplies are a money-maker and feel comfortable absorbing a cost increase elsewhere, when in fact the supplies line has been running behind for months. Either way, you're guessing instead of knowing.
A worked example
Say you charge $6 per repair order for shop supplies, and you write 42 repair orders in a month. That's $252 in shop supplies income.
Now say you track what you actually bought that month: a case of shop rags, two jugs of degreaser, a box of nitrile gloves, zip ties, and a bag of mixed hardware. Add up the receipts and it comes to $310.
You charged $252 and spent $310. You're $58 short for the month, which means the shop supplies fee didn't fully cover what you spent. If that gap repeats most months, it's not a bad month, it's a fee that's too low.
The only way you'd know this is if shop supplies income and shop supplies cost sat in two separate accounts where you could look at them side by side. If they're both buried in "shop expenses" or mixed into parts cost, the $58 gap disappears into the noise.
How to set it up
- Create a shop supplies income account. In QuickBooks Online, set up an income account called "Shop supplies income," separate from labor and parts income. Make sure your point-of-sale or invoicing system maps the shop supplies line on repair orders to this account.
- Create a shop supplies cost account. Set up a matching expense account called "Shop supplies cost." This should only hold the consumables you use across jobs generally: rags, cleaners, gloves, tape, small hardware, and similar items.
- Keep it separate from parts cost. Parts that go into a specific customer's vehicle belong in cost of parts sold, not shop supplies. Shop supplies are the things you use across jobs that don't get billed individually.
- Code purchases consistently. When you buy a case of rags or a box of fasteners, code it to shop supplies cost every time, not sometimes to "general expenses" and sometimes to "shop supplies." Consistency is what makes the monthly comparison mean something.
- Run the comparison monthly. Pull the total for shop supplies income and the total for shop supplies cost for the same month. Look at the gap in dollars, not just as a feeling.
- Adjust the fee if the gap is consistent. If you're consistently short, consider whether your flat fee or percentage needs to go up. If you're consistently ahead, you'll at least know that with certainty instead of assuming it.
What undoes it
- Letting the fee mapping drift. If your invoicing system ever gets reconfigured or a new service writer sets up a repair order template, the shop supplies charge can accidentally get coded to general sales instead of the dedicated income account.
- Mixing supplies with parts. If a tech grabs a case of brake cleaner and it gets coded to parts cost because that's where the purchase order defaults, your shop supplies cost will look artificially low and the comparison becomes useless.
- Only checking once a year. A once-a-year glance doesn't catch the month a supplier raised prices or the month you ran three heavy jobs back to back. Monthly is what makes the pattern visible.
- Treating one bad month as the whole story. A single month of being short doesn't mean the fee is wrong. Look for a pattern across several months before changing anything.
Monthly checklist
- Pull total shop supplies income for the month from repair orders.
- Pull total shop supplies cost for the month from receipts and purchase records.
- Compare the two numbers and note the gap, positive or negative.
- Check that no shop supplies purchases got coded to parts cost or general expenses by mistake.
- If the gap has been consistent for three or more months, consider adjusting the flat fee or percentage.
Common questions
What counts as a shop supplies cost versus a parts cost?
Shop supplies are consumables used across many jobs that aren't billed to a specific customer line item: rags, degreaser, gloves, tape, small generic hardware. If an item goes directly into one customer's vehicle and could reasonably be itemized on that repair order, it's a parts cost, not a shop supplies cost. Where a specific item falls can depend on how your shop bills, so it's worth deciding this once and writing it down so everyone codes it the same way.
Should the shop supplies fee be a flat dollar amount or a percentage?
Both approaches are common, and the right choice depends on your mix of work. A flat fee is simple but can undercharge on bigger jobs that use more supplies. A percentage of labor scales with job size but can overcharge on quick, simple jobs. Either way, the fee should be checked against actual cost periodically rather than set once and forgotten.
How often should I actually change the fee?
There's no fixed schedule. The point of the monthly comparison is to build a record over several months so you can see a real pattern rather than reacting to one unusual month. Many shops find it useful to revisit the fee once or twice a year if the gap has been consistent.
Can QuickBooks Online automate this tracking?
QuickBooks Online can hold the separate income and expense accounts and make it easy to run a report comparing them each month. It won't code purchases correctly on its own, so someone still needs to make sure shop supplies purchases are consistently assigned to the right account.
North Hudson Bookkeeping sets up this kind of tracking for repair shop clients and keeps it current month to month, so the comparison is always ready when you want to look at it. The first call is free.
