Illinois Automotive Repair Act: Estimate Rules for Jobs Over $100, the 10% Limit, and What Mobile Mechanics Must Disclose

Updated 2026-10-17. Sources are listed at the end.

Illinois regulates what you tell customers, not who can turn a wrench. Under the Automotive Repair Act (815 ILCS 306), “no work for compensation that exceeds $100 shall be commenced without specific authorization from the consumer” after the required disclosures (815 ILCS 306/15).

Two kinds of estimate: pick one per job

Every repair facility must either (815 ILCS 306/15(b)):

1. give a written estimated price for labor and parts and not exceed it by more than 10% without the customer’s oral or written consent, or
2. give a written price limit and not exceed it at all without consent.

Either way, the estimate must show the total cost of the repair, including charges for estimates and diagnostics, plus the expected time if the job takes more than one working day.

Mobile tip: option 1 gives you a 10% cushion. Option 2 gives you none. If you quote flat prices, every surprise needs a call.

What the estimate must say

From 815 ILCS 306/15(b)(1)-(5) (ILGA):

• the major parts needed, and whether they’re new or used
• a statement that labor may be calculated using flat-rate manuals, actual time, or the vehicle’s condition (a posted sign can satisfy this, but a mobile tech has nowhere to post one, so put it on the form)
• whether each repair is required or suggested
• disassembly/reassembly charges if you have to take something apart to estimate it and the customer declines the repair
• the date, the odometer reading, and a promised delivery date

The firm-price exemption

The estimate rules don’t cover “the retail purchase of merchandise when a facility installs the merchandise as part of the transaction at the discretion of the customer for a firm price,” including tires, batteries, oil, and lube jobs (815 ILCS 306/15). The Attorney General adds that the Act doesn’t apply to collision repairs or repairs under $100 (IL AG summary). A posted-price battery swap or oil change can fall outside the estimate rules. A diagnosis doesn’t.

Phone approvals and unforeseen work

If the price will go over because of something unforeseen, get the customer’s oral or written consent first. For phone approval, the AG says to note the date, time, name of the person authorizing, their phone number, and the added cost on the estimate or invoice (IL AG).

Invoices, liens and signs

Per the Attorney General’s summary of the Act (IL AG):

• Invoices must itemize parts and labor and show the odometer reading, any warranties, and the total.
• You can’t assert a lien for unauthorized repairs.
• Shops must post customers’ rights where customers can see them. Mobile techs should print the same rights on the estimate.

Illinois checklist

1. Choose itemized estimates (10% cushion) or price-limit estimates (no cushion) and use the same method on every job.
2. Add the labor-calculation statement and “required / suggested” tick boxes to your form.
3. Write down the odometer reading and a promised date on every estimate.
4. Log phone approvals with date, time, name, number and amount.
5. Quote carefully so you rarely need that call: use the job quote & profit calculator.

Compare with Colorado’s 10%/$25 rule, Washington’s 110% cap, and CA, FL and NY estimate rules.

More on this topic

• Customer won’t pay? Getting paid before you leave
• Mobile mechanic diagnostic fees
• Do you need a license to be a mobile mechanic?

Sources

• 815 ILCS 306/15, Disclosures to consumers; estimates: https://ilga.gov/documents/legislation/ilcs/documents/081503060K15.htm
• Illinois Attorney General, Automotive Repair Act: Consumer’s Rights Under the Law: https://www.illinoisattorneygeneral.gov/Page-Attachments/IllinoisAutomotiveRepairAct.pdf