Flat rate vs time and materials pricing for plumbers
2026-10-11 · 7 min read
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It is a Tuesday and the shop has two calls before lunch. The first is a kitchen drain backing up into the sink. The second is a homeowner whose galvanized supply line is leaking somewhere behind the laundry room wall. Both customers ask the same thing at the door: what is this going to cost?
On the drain, the tech has an answer. On the wall, he does not know until the drywall is open. How the shop prices those two jobs decides how much office work follows each one home.
The short answer
Flat rate works best for the jobs you do every week, where the work is predictable and the customer wants a number before you start. Time and materials works best when nobody can see the job until it is opened up: older homes, remodel work, leaks you have to trace. A lot of small shops run both, and the trouble starts when the rule for which one applies lives in the owner's head instead of on paper.
Flat rate vs time and materials, side by side
| Flat rate | Time and materials | |
|---|---|---|
| What the customer sees | One price before work starts | An hourly rate and parts, totaled after |
| Who carries the risk of a slow job | The shop | The customer |
| Best fit | Repeat service work: drains, faucets, toilets, water heater swaps | Jobs you cannot see until they are open: tracing leaks, old piping, remodels |
| Where the office work piles up | Keeping the price book current | Explaining and defending the final invoice |
| When the customer says yes | At the door, before the tools come out | Often never formally, which is the problem |
| How invoicing goes | The invoice matches the approved price | Someone rebuilds the day from notes and receipts |
| The common failure | Book prices from last spring on this fall's parts | A bill the customer did not expect and calls to argue |
What each one costs the office
With flat rate, the work moves upstream. The price is only as good as the book behind it. Somebody has to set each price from parts, labor and drive time, then keep it current when the supply house raises its numbers. When that upkeep slips, every water heater sells at an old margin and nobody notices until the year closes. I wrote about that slow leak in the post on weekly job costing for plumbers. The other upstream cost is the tech in the driveway, flipping through a binder or calling the office while the customer waits.
With time and materials, it moves downstream. The quote is easy because there is barely a quote. The cost shows up after. Somebody has to rebuild the day: which parts came off the truck, which came from the counter, why a two-hour job ran four. Then the invoice goes out and the customer calls, because the number is larger than the one they had in their head and nothing written ever told them otherwise. That call tends to land on the owner in the evening, and it often ends with a discount that came out of the profit on the job.
Both methods share one hidden cost: the switch between them. A tech who should have quoted a flat price goes hourly because the book did not cover the job. A tech who should have gone hourly gives a flat price on a leak he has not found yet, and the shop eats the difference. Without a written rule, every tech draws that line in a different place.
What replacing the hand work looks like
Nothing here changes how you price. It takes the retyping and the remembering out of whichever method you use.
Under flat rate:
- The price book lives in one place your field software and your quotes both read from, rather than in a binder on the dash.
- When a supplier invoice shows a part costing more than the book assumes, the system flags every price that uses it. You decide the new number. It does not change prices on its own.
- On site, the tech picks the job and the options, and the customer gets the quote by text with an approve button and a signature. The approved price becomes the invoice with no retyping.
- Quotes that were not approved on the spot get a follow-up on a schedule you set, and it stops the moment the customer answers.
Under time and materials:
- Before work starts, the customer approves a written estimate range by text, with a not-to-exceed figure if you use one. The system will not let a ticket go to "in progress" without that approval on file.
- When the job is about to pass the approved figure, the tech sends a change request from his phone with a photo and a line of explanation, and the customer approves it in writing before he keeps going.
- Time comes from the job clock in your field app, parts from the ticket and the supplier invoices. The system drafts the invoice with line items, photos and the approvals attached. Someone in the office reviews it before it goes out.
- When a tech opens a job type that is not in the book, the written rule for hourly work shows up as a prompt.
A shop that prices most jobs one way only needs that half. If you are still deciding how to price over the phone before anyone visits, the comparison of ballpark prices and on-site estimates covers that earlier step.
What stays human
Setting prices stays with you. A system can tell you the counter price of a 50-gallon heater went up. It cannot tell you whether your market will pay more for the swap, or whether you want to hold the price to keep the plumbing contractor down the road from taking those calls.
The judgment at the door stays with the tech. Whether a leak is a flat-rate repair or an hourly trace depends on what he finds when he opens the cabinet, and no rule written in an office covers every house in the Fox Valley.
The hard conversation stays with a person too. When a job runs far past the estimate, the customer should hear it in a phone call from someone at the shop, with the approval text following behind it as the record. A customer who feels surprised by a bill wants to talk to a person, and I would not put a script between them.
When the choice barely matters
If you run one truck, answer every call yourself, and work mostly for neighbors who trust your number, either method works and the hand work is small enough to carry. If your field service app already handles quotes, approvals and invoices well, the gaps are usually the price book alerts and the follow-up on unapproved quotes. I would wire those to the tool you have and leave the rest.
It is worth building when the owner is the one updating prices, explaining invoices and chasing approvals after the trucks come back. Builds start at $500 one-time, then a flat monthly from $99 after an included run-in period, cancellable. There is more on what I set up for plumbing contractors.
Where to start
Start with the free 20 minute process audit. We walk one week of tickets, sort them into flat rate and hourly, and find where the office spent its time: on the book, at the door, or on the phone after the invoice went out. You will know which half of this is worth automating, and you keep the map either way. Book the audit here.