17c Diminished Value Formula: How It Works (With Examples)

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:

1. Start with the pre-loss value (NADA, KBB, or appraised).
2. 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).
3. Apply a damage multiplier (0.00 to 1.00) based on severity.
4. 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.