Cash leaves no trail, so the paper is your only proof. Under A.R.S. 32-1158(B), when a contractor and an owner sign a contract, the contractor must give a signed receipt for the true amount of any cash paid. A written invoice also backs warranty claims and any Registrar of Contractors complaint.
Is a written receipt for cash actually required in Arizona?
Sometimes, and it's worth knowing the exact wording. Arizona's contractor licensing law says: "When a contractor and an owner sign a contract, the contractor shall provide the owner with a legible copy of all documents signed and a written and signed receipt for and in the true amount of any cash paid to the contractor by the owner." That is A.R.S. 32-1158(B).
Two details matter. First, the rule is tied to a signed contract. The part of that section listing what a contract must contain applies to contracts "in an amount of more than $1,000," so a small same-day repair with no signed paperwork may not trigger it. Second, the statute says failing to follow it does not erase the deal: the requirements are not "prerequisites to the formation or enforcement of a contract." So the law gives you a right to the receipt, not a guarantee the job goes well. Either way, ask for one. A plumber who does good work has no reason to say no.
What should the invoice show?
A useful invoice reads like a short record of the job. For a signed contract, Arizona's list in 32-1158(A) is a good model: the contractor's name, business address and license number, your name and the jobsite address, the date, a description of the work, and the total amount to be paid. For a cash job, add these:
- Amount paid, the date, and the words "paid in cash," with the plumber's signature.
- What was done. A line such as replaced 50-gallon gas water heater is better than just water heater.
- Equipment details. Brand, model and serial number of anything installed, because warranty claims run on them.
- The warranty on labor, and on parts, in writing. The Arizona Attorney General's consumer guidance says "If a contractor guarantees labor and/or materials, those warranties should be in writing."
- Permit number, if the work needed one. Our guide to whether a water heater swap needs a permit in Phoenix is a good example of work that does.
Why does the paper matter after the job is done?
Because most problems show up later. Here's where the invoice earns its keep.
- 1Warranty claims. Manufacturers want proof. Navien's warranty, for one, states: "Proof of the date of installation must be provided to Navien." A cash payment with no invoice makes that proof hard to produce. Our page on finding a water heater's age and warranty status shows what the serial number tells you, and the invoice covers the install date.
- 2Complaints. You can file a written complaint with the Arizona Registrar of Contractors, but only so long after the job. The statute says complaints must be filed "within two years after the completion of the specific project" for projects other than new construction. A dated invoice fixes the completion date and names the license to complain about.
- 3Records for your own use. The Attorney General's guidance says to keep "all records related to your project," which includes the contract, change orders, warranties and correspondence, and calls them important "particularly if you have a problem." Insurance claims, a home sale and a later repair all go smoother with the paper in a folder.
- 4Who got paid for what. If a subcontractor or supplier is not paid, the Attorney General's guidance notes they "may file a mechanics lien against your home." See Arizona lien waivers explained for how that works on bigger jobs.
Is paying cash a warning sign?
It can be. The Arizona Attorney General lists a contractor who demands "full payment up front, particularly if payment is demanded in cash" among the signs that someone is not operating within the law, and advises: "Never pay in full up front, especially if cash is the only payment accepted." A card or check gives you a record. If cash is the only option offered, treat that as a reason to look harder at who you are hiring: check the ROC license first, then decide.
What if the plumber won't write anything down?
Ask once, politely, and then decide whether to continue. Before they leave, take a photo of the finished work, the equipment label and the plumber's truck or license information, and write down the date, the amount and the person's name. That is a weak substitute, though. A contractor who will not put a cash payment in writing is telling you something. Our page on why a licensed, bonded and insured plumber matters explains what you give up when you hire someone who will not.
HQ Plumbing and Air is licensed and insured and gives free estimates with upfront pricing, so you know the scope in writing before work starts. If you are weighing who to call, see our local plumbing services or how to choose a plumber.