Diminished Value Claim in Illinois: What Not-at-Fault Drivers Need to Know
If another driver hit your car in Illinois and it lost market value even after repairs, you may be able to file a diminished value claim against their liability insurance. Illinois is a tort (fault-based) state, which matters a lot here — the at-fault driver's insurer, not yours, is generally on the hook for that lost value. This page walks you through how Illinois law applies, how to calculate your claim, and how to file it yourself. This is general information, not legal advice — consult a licensed attorney in your state.
Does Illinois Allow Diminished Value Claims?
Yes — Illinois recognizes diminished value as a compensable loss under third-party liability claims. Because Illinois follows a fault-based auto insurance system (not a no-fault system), you have the right to seek compensation directly from the at-fault driver's insurer for all damages caused by the accident, including the drop in your vehicle's resale value. Courts in Illinois have long held that property damage compensation should restore you to your pre-accident position, which includes market value loss.
One important distinction: first-party diminished value claims — filed against your own collision coverage — are typically not available in Illinois, and most standard auto policies exclude them. Your path is almost always a third-party claim against the at-fault driver's liability insurer. Verify your own policy language and, if needed, check with the Illinois Department of Insurance at insurance.illinois.gov.
Illinois Statute of Limitations for Diminished Value
Illinois property damage claims carry a five-year statute of limitations under 735 ILCS 5/13-205, running from the accident date. Don't wait — evidence fades and insurers become harder to deal with over time. File as soon as repairs are complete. Deadlines can vary; confirm with the Illinois Department of Insurance or a licensed attorney.
How to Calculate Your Illinois Diminished Value
Most insurers use the Industry Standard 17c formula as a starting point, though Illinois does not mandate it. The formula caps the base loss at 10% of your car's pre-accident actual cash value (ACV), then applies multipliers for damage severity and mileage. Here is the basic structure:
- Step 1 — Find your vehicle's pre-accident ACV using Kelley Blue Book (kbb.com) or NADA Guides.
- Step 2 — Multiply ACV × 10% to get the base diminished value cap.
- Step 3 — Apply a damage multiplier (0.00 for no structural damage up to 1.00 for severe structural damage).
- Step 4 — Apply a mileage multiplier (ranges from 1.00 for under 20,000 miles down to 0.00 for over 100,000 miles).
The 17c formula tends to undervalue losses — it was created by State Farm and is widely criticized as a floor, not a ceiling. An independent appraisal will almost always produce a higher number. Use the Car Value Back 17c calculator for a quick estimate, then submit a written demand letter to the at-fault driver's insurer with your documentation. Negotiate — first offers are rarely final. If denied, file a complaint with the Illinois Department of Insurance or consider small claims court for amounts up to $10,000. Your actual recoverable amount is not guaranteed.
What Illinois Adjusters Look For
Illinois adjusters weight structural damage heavily — frame damage, airbag deployment, or flood damage strengthens your claim significantly, while cosmetic-only damage yields a much lower multiplier. Vehicle age and mileage also matter: a three-year-old car with 30,000 miles loses far more market value than a high-mileage older vehicle. A Carfax or AutoCheck report showing the accident on record is useful supporting evidence.