17C: Why a Formula May Miss Your Vehicle’s Actual Loss

The 17C formula became associated with the litigation in State Farm v. Mabry. It generally starts with 10% of a vehicle’s pre-loss value, then applies damage and mileage modifiers.

CCSI has several appraisal concerns with this approach:

• The 10% starting limit: It limits the calculated loss before considering how the individual vehicle’s collision history affects its market value.

• Repair costs: The formula does not directly incorporate the full cost of repairs. Repair costs are not the same as diminished value, but the complete repair estimate provides important evidence of the extent and complexity of the damage.

• The damage modifier: Broad severity categories reduce a complex repair history to a single multiplier. That multiplier may not adequately distinguish between bolt-on panel replacement, welded panel replacement, structural repairs, or replacement of structural components. Its selection also involves judgment, so it should be supported by the actual damage and repair documentation.

• The mileage modifier: A separate mileage reduction may discount the result again when mileage is already reflected in the vehicle’s starting value. Higher mileage alone does not establish that collision history causes no additional market loss.

A repair bill alone cannot establish diminished value, and neither can a severity label. An appraisal should consider what was damaged, how it was repaired, repair quality, prior damage, and the effect of the collision history on the vehicle’s market value.

CCSI evaluates the individual vehicle and supporting information rather than treating a 17C calculation as the final answer.

I am not a lawyer. This information reflects my appraisal experience and is provided for educational purposes, not as legal advice. Consult an attorney about your legal rights or a disputed claim.