Illinois requires all drivers to carry liability insurance, but the state minimum limits are among the lowest in the country: $25,000 per person and $50,000 per accident for bodily injury. If you are seriously hurt in a crash and the at-fault driver carries only the minimum, their coverage may not come close to covering your medical bills—let alone lost wages, pain and suffering, and long-term care costs.

This is where your underinsured motorist (UIM) coverage becomes critical.

How Underinsured Motorist Coverage Works

UIM coverage pays the difference between the at-fault driver’s liability limits and your actual damages, up to your own UIM policy limits. Under 215 ILCS 5/143a, Illinois insurers must offer UIM coverage, though drivers may reject it.

Here is a simplified example:

You suffer $150,000 in damages from a crash
The at-fault driver carries $25,000 in liability coverage (the Illinois minimum)
You carry $100,000 in UIM coverage
The at-fault driver’s insurer pays $25,000
Your UIM coverage can pay up to an additional $75,000 (the difference between your $100,000 UIM limit and the $25,000 already received)

This offset calculation is standard in Illinois UIM claims, though the exact method depends on your policy language.

Why Minimum Coverage Is So Dangerous

A $25,000 policy limit can be exhausted by a single emergency room visit. Consider the costs of a moderate-to-serious car accident injury:

Emergency room visit: $5,000–$20,000
Surgery: $20,000–$100,000+
Physical therapy (12 weeks): $5,000–$15,000
Lost wages (3 months): $10,000–$30,000
Pain and suffering: Varies widely

A broken leg from a car accident can easily generate $75,000 or more in economic damages alone. If the driver who hit you carries only $25,000, you are left with a $50,000+ gap that UIM coverage is designed to fill.

Steps to Take When the At-Fault Driver Has Minimum Coverage

Confirm the at-fault driver’s limits. Your attorney can send a liability limits demand letter to the other driver’s insurer to verify coverage amounts.
Collect the liability limits. In many cases, accepting the at-fault driver’s full policy limits is appropriate. But consult an attorney first—accepting too early or without proper documentation can affect your UIM claim.
Notify your own insurer. Before settling with the at-fault driver’s insurer, notify your UIM carrier. Many policies require this to preserve your UIM rights.
File a UIM claim. Once the liability payment is resolved, file a UIM claim with your own insurer for the remaining damages.
Prepare for negotiation or arbitration. UIM claims are often disputed. If your insurer undervalues your claim, arbitration is the typical dispute resolution mechanism.

Can Stacking Increase Your Recovery?

If you insure multiple vehicles, you may be able to stack your UIM coverage to access higher limits. This is especially valuable when the gap between the at-fault driver’s coverage and your actual damages is large.

Protect Yourself Now

The best time to prepare for an underinsured driver crash is before it happens. Review your auto policy and make sure you carry UIM limits that reflect the true cost of a serious injury—not just the minimum. If you have already been injured and the at-fault driver is underinsured, contact Parker & Parker for a free consultation. We will identify every source of coverage available to you.

Frequently Asked Questions

Do I have to accept the at-fault driver’s policy limits before filing a UIM claim?

Usually, yes, but you must notify your UIM carrier before accepting the liability payment. Failure to do so can jeopardize your UIM claim.

What if my UIM limits are the same as the at-fault driver’s liability limits?

In Illinois, if the at-fault driver’s liability limits equal or exceed your UIM limits, you may not have a UIM claim because the other driver is not technically “underinsured” relative to your policy. This is why carrying higher UIM limits is so important.

Can I sue the at-fault driver personally for the difference?

You can, but collecting a judgment against an individual who carries only minimum insurance is often difficult. UIM coverage is typically a more practical path to recovery.

What Happens When the At-Fault Driver Has Minimum Coverage in Illinois?