When a customer supplies their own materials, you lose the material gross profit but keep every hour of labor, every warranty question, and every risk. The fix is a separate labor-only rate that recovers the lost margin — typically 25% to 50% above your standard hourly rate — plus a written policy on what you will and will not install. Charging your normal rate on a customer-supplied job is a quiet pay cut.
What customer-supplied materials actually cost you
"I already bought the faucet online — can you just install it?" sounds like a smaller job. It is not. It is the same truck roll, the same technician, the same drive, and the same callback exposure, minus the profit you earn on the part.
Here is the same plumbing service call priced two ways. Assume a 40% markup on material cost and a burdened labor cost of $62 per hour.
| Line | You supply the faucet | Customer supplies it |
|---|---|---|
| Material billed | $252 | $0 |
| Material cost | $180 | $0 |
| Material gross profit | $72 | $0 |
| Labor billed (1.5 hr @ $185) | $278 | $278 |
| Labor cost (1.5 hr @ $62) | $93 | $93 |
| Labor gross profit | $185 | $185 |
| Total gross profit | $257 | $185 |
Same truck, same 1.5 hours, 28% less gross profit. Do four of those a week and you have given away roughly $15,000 a year in margin without changing a single price on your rate sheet.
That hurts more in some trades than others. Plumbing service calls tend to run higher gross margins precisely because the material-to-labor ratio is low, while HVAC repair carries more parts cost per ticket — HVAC gross margins typically land in the 30–40% range against 45–55% for plumbing service. The more of your margin lives in parts, the bigger the hole a customer-supplied job leaves.
The job did not get cheaper. Only your invoice did.
The labor-only rate formula
The fix is not a vague "I charge a bit more." It is a second rate in your price book, calculated from the margin you are giving up:
Labor-only rate = standard hourly rate + (typical material gross profit per job ÷ typical billable hours per job) + risk adder
In the example above, recovering the $72 of lost material profit over 1.5 hours means adding $48 per hour. Your $185 rate becomes $233 — a 26% uplift before you price any risk at all. Estimating veterans have made this point for decades: on a labor-only job, every direct and indirect cost has to be absorbed into the labor rate, because there is nowhere else for it to go.
Here is what that uplift looks like across trades. These are illustrative starting points — run your own averages from last quarter's invoices.
| Trade | Typical material GP per service job | Typical billable hours | Rate uplift needed |
|---|---|---|---|
| Plumbing service | $72 | 1.5 | +$48/hr |
| Electrical service | $55 | 2.0 | +$28/hr |
| HVAC repair | $120 | 2.0 | +$60/hr |
| Appliance / fixture swap | $60 | 1.0 | +$60/hr |
Then add the risk adder — 10% to 15% on the labor line, or a flat handling fee of $50 to $100. That is not padding. It pays for the extra trip when the part is wrong, the time spent inspecting something you did not source, and the diagnostic hour you will eat when it fails in six weeks.
If the markup-versus-margin math is where you get tripped up, the free margin and markup calculator converts between the two in one step, and our markup vs margin guide covers why a 40% markup is not a 40% margin.
The risks you are accepting for free
Money is only half of it. When you install a part you did not buy, three things shift onto you at no charge.
You inherit the warranty conversation
Your workmanship warranty still applies. The part's does not — and the customer will not remember the difference at 9pm when the unit quits. Many shops handle this by warranting labor for 12 months on parts they supply, and stating in writing that customer-supplied material and the labor to replace it are covered by the manufacturer only.
One nuance worth knowing: the Magnuson-Moss Warranty Act stops a manufacturer from voiding a consumer warranty simply because a third-party part or independent shop was used — they have to show the part actually caused the failure. That is a constraint on manufacturers, not on you. Your own warranty terms are yours to set, and you are entitled to exclude material you did not supply.
You absorb the second trip
Wrong size, missing gasket, discontinued trim kit, the box that turns out to be a return someone resealed. When you source the part, a mistake is a phone call to your supplier. When the customer sources it, a mistake is an unpaid return visit. Price that the same way you price any other rework — see how to price for callbacks for the method.
You own the outcome either way
The customer bought a grey-market condenser online. It fails. Your name is on the invoice, your van was in the driveway, and the online review is about you. On system-level equipment, this risk is usually not priceable at any rate — which is why most shops simply decline it.
Three policies that actually work
| Policy | When it fits | What to charge |
|---|---|---|
| Decline outright | Equipment installs, anything you warranty as a system, used or grey-market parts, refrigerant-circuit work | Nothing — offer to quote it supplied and installed |
| Accept at labor-only rate | Simple swaps, new OEM parts in an unopened box, fixtures and trim | Labor-only rate from the formula above, signed waiver on the part |
| Accept at standard rate plus handling fee | Small, low-risk items for a maintenance-agreement customer you want to keep | Standard rate + $50–$100 handling fee |
Whichever you choose, put it on the estimate in plain language before work starts — one line stating that customer-supplied material carries no warranty from you, and that a return trip caused by a defective or incorrect part is billable. Verbal versions of this policy do not survive contact with an unhappy customer.
How to set this up in your price book
A policy nobody can find is a policy nobody follows. Make it a real line item:
- Add a labor-only rate as its own service item, not a mental adjustment your techs apply in the driveway. Rate uplift baked in, description explaining what it covers.
- Add a handling fee item at a fixed price so it can be added to a quote in one tap.
- Add a waiver line — a zero-dollar line item whose description is your customer-supplied-material terms, so it prints on every affected estimate.
- Review the uplift quarterly. It is derived from your material gross profit, so when material costs or markups move, the labor-only rate has to move with them. Cost-band markups make this easier to keep straight — see material markup by cost band.
This is exactly the kind of derived rate that drifts out of date in a spreadsheet. Pricebookr keeps the master catalog, applies markup and margin rules in bulk, and syncs the result back to Jobber, so a change to your material markup can flow through to the labor-only rate in the same pass instead of being rediscovered a year later.
Key takeaway: a customer-supplied job is not a discount job. It is a higher-risk job with the profitable half of the ticket removed — price it accordingly, or turn it down.
FAQ
Should contractors install customer-supplied materials at all?
It depends on the part. Simple swaps with new OEM parts — fixtures, trim, a standard faucet — are reasonable to accept at a labor-only rate with a signed waiver. System-level equipment such as furnaces, condensers, and water heaters is usually worth declining, because you carry the install warranty and the reputation risk on a product you cannot verify.
How much more should I charge for labor-only work?
Enough to recover the material gross profit you are giving up, spread across the billable hours of the job, plus a risk adder. For most service trades that lands between 25% and 50% above the standard hourly rate. Calculate it from your own numbers: average material gross profit per job divided by average billable hours per job, then add 10–15% for risk.
Do I have to warranty a part the customer bought?
No. You warranty your workmanship; the part's warranty belongs to whoever sold it. State this in writing on the estimate — customer-supplied material and the labor to replace it are excluded from your warranty — and have the customer acknowledge it before work begins.
Does installing a customer's own part void the manufacturer warranty?
Not automatically. Under the Magnuson-Moss Warranty Act, a manufacturer cannot void a consumer warranty just because a third-party part or an independent shop was used; it must show that the part caused the failure. Manufacturers can still exclude damage genuinely caused by an unauthorized part, and equipment warranties often carry their own registration and licensed-installer conditions worth checking per brand.
Is a handling fee or a higher labor rate better?
A higher labor rate scales with the size of the job, so it is the better default for anything over an hour. A flat handling fee is simpler to explain and works well for quick, low-risk items or for customers you want to keep on good terms. Some shops use both: labor-only rate on the hours, flat fee for the administrative overhead.
How do I bring this up without losing the customer?
Quote both ways. Show the supplied-and-installed price next to the labor-only price with the warranty difference spelled out. Most customers who wanted to save $40 on a faucet choose the fully supplied option once they see that it costs little more and comes with coverage. The ones who do not are at least paying you properly for the risk.