17c Diminished Value Formula: How It Works (With Examples)
8 min read·Updated April 5, 2025
What diminished value is
Even after a perfect repair, an accident on your vehicle's history reduces resale value. That gap — between what your car would have sold for with a clean history and what it sells for with the accident on Carfax — is diminished value.
When you can claim it
- Third-party claims in most states. The at-fault driver's liability insurer owes you the loss in market value.
- First-party claims in Georgia (and a handful of others) where state law specifically allows it.
The 17c formula
Originated from a 2001 Georgia case (State Farm v. Mabry). The formula:
- Start with the pre-loss value (NADA, KBB, or appraised).
- Apply a 10% cap as the "base loss of value" (this is where the 17c name comes from — it's section 17(c) of the State Farm internal claims manual).
- Apply a damage multiplier (0.00 to 1.00) based on severity.
- Apply a mileage multiplier (0.00 to 1.00).
Why insurers love 17c
The 10% cap is arbitrary and almost always understates real-world diminished value. A $40,000 luxury SUV with structural damage can lose $8,000–$12,000 in market value, but 17c caps the claim near $4,000.
What actually wins
A market-based appraisal that pulls real comps for your repaired vehicle and compares them to comps with clean histories. This typically beats 17c by 2–3x for moderate-to-severe damage.
Frequently asked questions
Diminished value is the loss in resale price a vehicle suffers after being repaired from a collision, even when repairs are done perfectly. A car with a clean history sells for more than an identical car with an accident record.
The most common method is the '17c formula' — ACV × 10% cap × damage modifier × mileage modifier. Independent appraisers also run market comp analyses comparing post-repair value to pre-loss value.
In most states, no — first-party diminished value is rarely covered. Third-party claims (when the other driver is at fault) are recoverable in most states.
Statutes of limitation range from 2–6 years depending on the state. File as soon as repairs are complete and you have a finalized post-repair valuation.
Yes. We prepare the valuation, draft the dispute letter, and represent you in the appraisal-clause process if it gets that far. $1,000 minimum recovery or you pay nothing.