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Estimates and invoices for plumbers, from the first call to the last payment.
A plumbing job changes while you work on it. The price you said at the sink is not always the price once the wall is open. Here is how to keep the paperwork honest when that happens.
By Abrar · Updated · 8 min read
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The short answer
A plumbing job has three moments that need paper: the price you give before you know the cause, the extra you find behind the wall, and the final balance after the permit is signed off. Write each one down and get a yes before you go on. InvoiceWren keeps the estimate, the signed changes, the deposit and the payments on one job, so the balance is never a guess.
How a plumbing job runs on paper
Most jobs follow the same eight steps. The steps that cost plumbers money are the ones where something is said out loud and never written down.
- 1
The call
A customer calls about a leak, a clog or no hot water. Write down the address, who owns the house, what they say is wrong and whether it is an emergency. A rental needs the landlord to say yes.
- 2
The visit and the service fee
You look, find the cause and say what the visit costs. Many plumbers apply the service fee to the repair if the customer says yes. If you do, say so on the estimate, so nobody is surprised.
- 3
The price
A small repair is often a flat price said on site. A water heater, a repipe or a sewer line needs it in writing: what is replaced, the brand and model, labor, the permit fee, the old unit taken away, and what is not included, such as drywall or paint.
- 4
The yes, and the deposit
For a bigger job, get a signed estimate. Ask for a deposit only for what you must buy first. In California the law caps the down payment on a home improvement contract at $1,000 or 10 percent of the price, whichever is less [1].
- 5
The permit and the inspection
A water heater swap often needs a permit and an inspection. In Kirkland, Washington, for example, a gas water heater needs a mechanical permit, an electric one needs a plumbing permit, and the city says to schedule the inspection within 48 hours of the install [2]. Your own city will have its own rules. Ask the building department.
- 6
The work, and what you find
Opening a wall or digging a line can show a second problem: a corroded valve, a cracked drain. Stop, take a photo, price the extra and get a yes before you start it. In California a change to the price or the work has to be a written change order, signed by both sides before the change [1].
- 7
The final invoice
It lists the first scope, each approved extra, parts, labor, the permit fee, tax if it applies, the deposit paid and the balance. Whether tax applies depends on your state and on whether the building is a home or a business [3][4].
- 8
The payment and the receipt
Card, check, bank transfer or Zelle. Emergency jobs are often paid at the door. Write down the date, the amount and how it was paid, and give a receipt.
Where plumbing paperwork goes wrong
Most of these start with a price given before the cause was known.
A price given before the cause is known
The customer says "a leak under the sink". You quote a new trap. Behind it you find a corroded supply line and a bad shutoff valve. Now you either lose money or surprise the customer.
What to do: Write the estimate as "diagnosis and likely repair". Say what it covers. List the things that would be a change, such as a valve or a supply line.
Extra work on a spoken yes
The customer agrees at the sink. Two weeks later they argue about the bill. In California, a change in price or scope has to be done by a written change order signed by the customer and the contractor before the change [1].
What to do: One line per extra, with its price, approved before you start. A photo of the problem beside the line helps.
A deposit that is too big, or out of step with the work
In California, the down payment on a home improvement contract cannot be more than $1,000 or 10 percent of the price, whichever is less. Payments also cannot be more than the value of the work done so far [1]. Other states have their own rules.
What to do: Tie each payment to a stage: materials bought, rough-in done, final. Check your state before you ask for half up front.
Sales tax on the wrong part
In Texas, labor to repair residential property is not taxable, but the whole charge for repairing nonresidential property is [3]. In New York, repair and installation work is taxable and a capital improvement is not [4]. Charge it wrong and either the customer is overcharged or you owe it later.
What to do: Show labor and materials as separate lines. Learn your state rule. Ask an accountant if the job sits between the two.
Work that needs a license you do not hold
A helper or a handyman does plumbing without the right license, or a business advertises plumbing without one. In Florida, advertising yourself as available as a contractor without the right certification is a first-degree misdemeanor, and a felony for a repeat [5]. In California, a license is needed when a project is valued at $1,000 or more in labor and materials, needs a building permit, or uses employee labor [6].
What to do: Check what your state allows before you quote. Put your license number on the estimate and the invoice.
A final inspection nobody priced
The work is done. The inspection is two weeks away. The customer will not pay the last invoice until it passes, and your money is stuck.
What to do: Put the permit fee and the inspection on the estimate as lines. Write in the terms that the final payment is due after the inspection passes.
What InvoiceWren does for a plumber
Everything below happens on your phone, in the customer's kitchen, while the water is still off.
Estimates your customer signs on the spot
Write the estimate on your phone, add the permit and the disposal fee, and send it. Your customer reads it and signs on their own phone. No printing, no clipboard.
Saved items for the lines you type every week
Save the service call, the flex connector set, the expansion tank and the permit pass-through. The next estimate takes a tap per line.
A photo beside the price
Add up to 3 photos to a line. When you find a corroded valve, the photo sits beside its price, so the customer sees what you saw.
Change orders that need a yes
Found a second problem? Send a change order. Your customer approves it before you start. A change that is waiting is never counted as approved.
Deposit, balance and payments on one job
Send a deposit invoice from the approved estimate. The final invoice shows the estimate, each approved change and each payment, line by line, so the balance is explained.
Paid by Zelle, bank transfer or your own link
Your customer pays you directly. We take no fee on payments. They tap "I've paid", you check your account and confirm, and the receipt goes out.
Reminders you can turn off
If an invoice is late, InvoiceWren emails your customer for you. You choose the schedule, and it stops when they pay.
Estimates and approval · Change orders · Deposits, progress and final invoices · Getting paid and receipts
Need a document right now? Make a free estimate or a free invoice with no sign-up, then bring the job into InvoiceWren when you are ready.
Rules to check, by state
Plumbing is licensed and taxed state by state, and permits are set by your city or county. These are examples from official pages we read on Nov 13 2026. They are not a list of every rule. Check yours.
- Most states and some localities require plumbers to be licensed [7].
- California: a written contract is required for home improvement projects over $500. The down payment is capped at $1,000 or 10 percent of the price, whichever is less. A change needs a written, signed change order before the change [1].
- California: a license is needed when a project is valued at $1,000 or more in labor and materials, needs a building permit, or uses employee labor [6].
- Florida: there is an exemption for small, minor work with a total price under $2,500. It does not cover part of a larger job, or anyone who advertises as a contractor [8]. Ask the state board whether your kind of work can use it.
- Texas: labor to repair residential real property is not taxable. The whole charge to repair nonresidential real property is taxable [3]. That publication is dated Mar 2007, so confirm it with the Comptroller.
- New York: repair, maintenance and installation work is taxable. Capital improvement work is not [4].
- Permits: one city, Kirkland, Washington, lists a permit for a water heater swap and asks for an inspection within 48 hours [2]. Your city may differ.
This is general information, not legal or tax advice.
Checklist
Questions
Do I need a license to do plumbing work?
In most states, yes. The Bureau of Labor Statistics says most states and some localities require plumbers to be licensed [7]. The rules differ from state to state, so check your state board before you quote.
Can I charge a service call fee and then take it off the repair?
Yes, many plumbers do. Write it on the estimate, for example "service call $95, credited if you approve the repair", so the customer knows before they say yes.
How big a deposit can I ask for?
It depends on the state. In California, the down payment on a home improvement contract cannot be more than $1,000 or 10 percent of the contract price, whichever is less [1]. In other states, check the home improvement or contractor law.
Do I need a signed change order for extra work?
California's home improvement contract rules require a written change order, signed before the change [1]. In other states it is still the safest way to avoid a dispute.
Do I charge sales tax on my labor?
It depends on the state and on the building. In Texas, residential repair labor is not taxable and nonresidential repair is [3]. In New York, repair work is taxable and a capital improvement is not [4]. Ask your state tax office or an accountant.
What do I do when I find a bigger problem after the customer said yes?
Stop, show them, price it as its own line and get a yes before you go on. With InvoiceWren, you send a change order and they approve it on their phone.
What should a plumbing invoice show?
The first scope, each approved extra, parts, labor, the permit fee, tax if it applies, the deposit paid and the balance. The final invoice in InvoiceWren builds that from the job, so the numbers match the estimate.
What if the customer will not pay until the inspection passes?
Put it in the terms before you start: final payment is due after the inspection passes. Some cities ask for the inspection soon after the install, such as 48 hours in Kirkland, Washington [2].
Can I sell a repair at the customer's home and have it cancelled later?
The Federal Trade Commission has a rule for some sales made at home that gives the buyer three business days to cancel [9]. Whether a service call counts depends on the sale. Ask a lawyer or your state office if you are not sure.
Send your next estimate from the job.
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Sources
- California Contractors State License Board: What is a Contract?. Checked .
- City of Kirkland, Washington: Water Heater Replacement. Checked .
- Texas Comptroller: Real Property Repair and Remodeling (publication 94-116). Checked .
- New York State Tax Department: Contractors, Repair, Maintenance, and Installation Services to Real Property. Checked .
- Florida Statutes section 489.127, Prohibitions and penalties. Checked .
- California Contractors State License Board: What is illegal contractor activity?. Checked .
- U.S. Bureau of Labor Statistics, Occupational Outlook Handbook: Plumbers, Pipefitters, and Steamfitters. Checked .
- Florida Statutes section 489.103, Exemptions. Checked .
- Code of Federal Regulations, 16 CFR 429.1: Cooling-Off Rule, unfair or deceptive acts or practices. Checked .
Prices and features change. We check these pages before each update. If something here is out of date, tell us at hello@invoicewren.com and we will fix it.