Does Illinois Allow UM/UIM Stacking? What Sections 143a and 143a-2 Say

By the FigureMyTax Editorial Team · How we calculate

Illinois bars aggregating UM limits across vehicles or policies, and its UIM statute lets an insurer provide that recovery under several policies equals but does not exceed the higher limit.

UM: section 143a

Section 143a(1) requires UM and hit-and-run coverage in the limits of the financial responsibility law for people legally entitled to recover from owners or operators of uninsured and hit-and-run vehicles, and says UM limits on one vehicle under the policy may not be aggregated with similar coverage on other vehicles, from the same insurer or another, to find the total limit for one crash. Disputes about coverage and damages must go to American Arbitration Association arbitration.

Additional UM and rejection

Section 143a-2(1) and (2) requires UM in an amount equal to your bodily injury liability limits unless a named insured or applicant rejects coverage in excess of the statutory minimum by a written request for lower limits or a written rejection. That binds all insureds, and the insurer need not offer more on renewal unless you ask in writing.

UIM: the policy-terms rule

Subsection (5) says nothing prohibits an insurer from providing that, if you have coverage under more than one policy or provision, any recovery may equal but not exceed the higher of the applicable limits, and that limits are not increased because of multiple vehicles under the same policy. Insurers may also provide UM and UIM in a combined coverage where the limits are the same.

What it leaves open

The text does not say what applies to UIM if a policy has no such term. A law-firm compilation of Illinois subrogation law and other secondary sources discuss case law on this; we did not read it. Ask an attorney before assuming your policies add up or do not.

How to use this

Compare the single-limit and combined results in the Illinois UM/UIM stacking calculator, start with the plain-English stacked versus single-limit explainer, and read how UM and UIM pay differently.

This is general information, not legal advice, and the state comparisons above are illustrative, not an exhaustive survey. Confirm how Illinois's rules apply to your specific case with a licensed Illinois attorney.