6.4 Part C Uninsured/Underinsured Motorists

Part C - Uninsured and Underinsured Motorists

Part C pays the insured's own bodily injury damages when those damages are caused by an uninsured (UM) or, in many states, an underinsured (UIM) motorist who is legally liable but cannot pay. It is the mirror image of Part A: instead of paying the people the insured injures, Part C steps into the shoes of the negligent other driver who has no adequate coverage, so the insured can still collect the damages the law entitles them to.

Uninsured vs. underinsured motorist

• An uninsured motor vehicle is one with no liability coverage at all, one whose insurer denies coverage or is insolvent, or a hit-and-run vehicle whose owner/driver cannot be identified.
• An underinsured motor vehicle has liability coverage, but its limits are lower than the UIM limits on the insured's own policy - enough to license but not enough to fully pay the loss.

UM coverage applies to BI in nearly all states; UM property damage (UMPD) is optional or unavailable depending on the state. UIM is purchased separately or combined and addresses the gap between the at-fault driver's low limit and the insured's own UIM limit.

Who is an insured and the legal-liability trigger

The Part C insured definition mirrors Parts A and B: the named insured, resident family members (covered in any auto or as pedestrians), and any other person occupying your covered auto. Two conditions must be met before Part C pays:

1. The other (uninsured/underinsured) driver must be legally liable for the injury, and
2. The insured must be legally entitled to recover damages from that driver.

Because the insured must be legally entitled to recover, Part C does not pay if the insured was wholly at fault. Most states require the insurer to offer UM/UIM limits equal to the Part A liability limit, and the insured must reject in writing to carry lower limits.

Worked underinsured-motorist calculation

UIM fills the gap. Suppose the insured suffers $100,000 of provable BI damages. The at-fault driver carries only $25,000 of liability; the insured carries $100,000 UIM. Two methods exist, and exams usually test the common difference (gap) approach:

Under the difference approach, UIM pays $100,000 - $25,000 = $75,000, so the insured is made whole at $100,000. Some states instead use an "excess" (limits-stacking) approach that pays UIM only on damages above the insured's own limit; for the national exam, use the difference method unless a question states otherwise.

Watch the trigger: UIM only responds when the at-fault driver's BI limit is lower than the insured's UIM limit. If both carried $100,000 and the at-fault driver's full $100,000 paid, the difference is zero and UIM pays nothing even though the insured is not fully compensated. UIM closes a gap between two limits; it does not turn the insured's policy into unlimited coverage. Likewise, UM/UIM is bodily injury only in most states - property damage to the insured's car runs through Part D collision or optional UMPD, not standard Part C.

Key Part C exclusions and traps

• Part C does not apply if the insured settles with the at-fault party without the insurer's consent, which prejudices the insurer's subrogation rights.
• The covered auto must not be one owned by the insured but not insured for UM under the policy (the "phantom owned vehicle" trap).
• For hit-and-run UM claims, there is usually a requirement of physical contact (in many states) or independent corroboration, and prompt reporting to police.
• A vehicle owned or operated by a self-insurer or a government-owned vehicle may be excluded from the "uninsured" definition.

Remember: Part C pays the insured's injuries (first-party), while Part A pays the other party's injuries (third-party). Confusing the two is the single most common Part C exam error.

Stacking, Offsets, and the UM/UIM Trigger Rules

Part C steps in when the at-fault driver has no insurance (UM) or not enough (UIM). The exam tests the trigger and the math.

• UM trigger: a legally liable uninsured motorist (no policy, denied claim, or a hit-and-run phantom vehicle in many states) injures the insured.
• UIM trigger: the at-fault driver has some liability coverage, but less than the insured's damages - UIM pays the gap up to the insured's UIM limit.

Exam trap: UM/UIM pays bodily injury the insured is legally entitled to recover from the other driver - so the insured must prove the other driver's fault. It is not automatic and generally does not cover the insured's own at-fault injuries.

Offset vs. Add-On States

States differ on how UIM is calculated: a limits-offset state subtracts the at-fault driver's limit from the insured's UIM limit, while an add-on (excess) state lets UIM stack on top. Stacking across multiple owned vehicles may be allowed or barred by policy language and state law. Because these rules vary, UM/UIM is a frequent place where the state-specific chapter (South Dakota's mandatory 25/50 UM/UIM) overrides the generic national default.