Stacked vs. Single-Policy UM/UIM Coverage in Idaho

By the FigureMyTax Editorial Team · How we calculate

Stacking adds the uninsured and underinsured motorist limits of several policies or vehicles together. Idaho's statute does not address it, so the answer turns on your policy's wording and on court decisions.

What stacking means

A household may have more than one policy, or more than one vehicle with UM/UIM. Stacking adds those limits after one injury, so $100,000 and $50,000 become $150,000. Single-policy coverage pays only the highest applicable policy. It matters only when your damages are larger than a single limit and larger than the at-fault driver's coverage.

What the statute says

Idaho Code 41-2502 requires UM and UIM coverage, in the limits of the financial responsibility law, for people legally entitled to recover damages from uninsured and underinsured drivers. It says nothing about adding limits together, or about "other insurance" or anti-stacking clauses.

What secondary sources report

A law-firm summary of Idaho UIM stacking reports that Idaho allows both inter-policy and intra-policy stacking unless the policy explicitly prohibits it, that the Idaho Supreme Court has declined to enforce an anti-stacking clause in one case and enforced a clear one in another, and that selling UIM at the same amount as the minimum liability limits has been held to be illusory. We did not read the decisions, so treat that as a lead.

A worked example

Suppose you are an insured under two policies with $100,000 and $50,000 of UM, and an uninsured driver causes $250,000 of damages. If both count, the UM can reach $150,000. If only the higher policy counts, it is $100,000. Try your own numbers in the Idaho UM/UIM stacking calculator, which shows both.

What to check

Read the UM/UIM section and the "other insurance" clause of each policy, and ask your insurer, in writing, which policies it says apply and why. See what the statute says and leaves open and how UM and UIM work in Idaho.

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