How to Write a Service Agreement or Contract

A surprising number of service businesses operate on nothing more than a verbal agreement and a text message thread. It works fine right up until a dispute happens — a delayed timeline, a scope disagreement, an unpaid balance — and there's nothing in writing to point to. A basic service agreement fixes this, and it doesn't need to be complicated.

What it needs to cover, at minimum

Parties and job address — who's doing the work and where
Scope of work — specific, itemized description of what's included (reuse language from your estimate)
Exclusions — what's explicitly not covered, to prevent scope creep disputes
Price and payment terms — total cost, deposit amount and timing, balance due date, accepted payment methods, and late fee terms
Timeline — start date and expected completion, with a note on what could cause delays (permits, material availability, weather)
Change order process — how added work gets approved and priced mid-job, in writing, before it happens
Warranty terms — what's guaranteed and for how long
Cancellation policy — what happens to the deposit and any ordered materials if either party cancels
Liability and insurance note — a brief statement that you carry liability insurance (and license number, where applicable)
Signatures and date — from both parties, even if it's just a typed name and a checkbox on a digital form

The change order clause is the one people skip and regret

Almost every job dispute traces back to added or changed work that was agreed to verbally mid-job and never priced or documented. A simple clause — "any additional work outside this scope requires written approval and updated pricing before starting" — combined with an actual habit of sending a quick change order for anything beyond the original estimate, prevents most billing disputes before they start.

Keep the language plain

A contract doesn't need to sound like a law firm wrote it to be enforceable and effective. Plain, specific language ("customer will provide clear access to the water heater location by the start date") is both more likely to be read and just as legally useful as dense legal phrasing, provided it's clear and both parties agree to it.

Digital signatures are enough for most jobs

For the vast majority of service work, a typed name with a timestamp, or a checkbox acceptance on a digital estimate, holds up fine as evidence of agreement. Save notarized or heavily lawyered contracts for large commercial jobs or situations your insurance or a lawyer specifically flags.

Have a lawyer review your template once

You don't need a lawyer for every job, but it's worth having one review your standard template once, especially the liability, warranty, and cancellation sections, since these vary by state and trade licensing requirements.

Make it part of every job, not just big ones

The businesses that avoid the most disputes apply a written agreement (even a short one) to every paid job, not just large installations. ServiQ's estimate approval flow doubles as this record — the accepted scope, price, and terms are captured and timestamped the moment the customer approves, so you're not maintaining a separate contract system on top of your estimates.