Labor or Parts: Which Side of Your Shop Is Actually Making Money?
Your P&L may say you made money — but it may not say where.
Your profit and loss statement may say you made money this month. It may not say where. That is the difference between a shop that feels busy and a shop that knows it is profitable.
Separate labor, parts, and sublet
Many shop books lump everything into “Sales.” That hides the answer to the only question that matters for pricing and staffing: are you making money on labor, on parts, or on neither?
In QuickBooks, that means separate income accounts for labor, parts, and sublet, and matching cost accounts for technician labor and parts cost of goods sold. Once they are separate, every monthly report can show the split without extra work.
Labor margin
Formula: (Labor sales − technician labor cost) ÷ labor sales.
Example: $10,000 in labor sales and $6,500 in labor cost is a $3,500 labor profit, or 35%. If labor margin is falling, look first at unbilled hours, discounts, and technician time that never made it onto a repair order.
Parts margin
Formula: (Parts sales − parts cost) ÷ parts sales.
Example: $8,000 in parts sales and $5,600 in parts cost is a $2,400 parts profit, or 30%. If parts margin is falling, look at pricing, core returns, and inventory that was sold but never recorded as cost.
What to do with the answer
If labor is carrying the shop and parts are not, the fix is usually pricing, parts handling, or core recovery — not simply “sell more.” If parts are carrying the shop and labor is not, the fix is usually billed hours, effective labor rate, or technician efficiency. You cannot choose the right fix from a single “Sales” line.
Texas sales tax: a short, important note
In Texas, separately stated repair labor is not taxed. That is, when labor is itemized separately from parts on the invoice, the labor charge itself is not subject to Texas sales tax.
Under a single, lump-sum price that does not itemize labor and parts separately, the shop does not collect tax from the customer on that price. Instead, the shop pays tax on the parts when it buys them. That is different from some other states, where an unitemized bill can be taxed in full — Texas does not work that way.
This is general information only, based on Texas Comptroller Publication 94-113: Motor Vehicle Repairs, Remodels and Maintenance. It is not tax advice for your specific situation; check with your CPA for how it applies to your shop.
Start with one month
Pick last month. Split it into labor, parts, and sublet, run the two margins above, and see which side did the work. That one page will tell you more than a year of “we were busy.”