Stacked vs. Single-Limit UM Coverage in Montana

By the FigureMyTax Editorial Team · How we calculate

Stacking adds the uninsured motorist limits of several vehicles or policies together. In Montana, limits may not be added only if the premiums actually reflect separate limits for each vehicle, the rates were filed, and the insurer told you in writing; otherwise the statute does not bar adding them.

What stacking means

A household may have more than one vehicle or policy with UM. Stacking adds those limits after one injury, so $50,000 and $50,000 become $100,000. Single-limit coverage pays only the one limit that applies.

What Montana law says

MCA 33-23-203 says that unless the policy specifically provides otherwise, the limits available are those of the policy insuring the vehicle involved, or, if that vehicle is not insured under a policy, the highest limits of one vehicle insured under one policy. The limits of one policy, or of several policies from the same company, may not be added together if the premiums charged actuarially reflect the limiting of coverage separately to the vehicles and the premium rates have been filed with the commissioner.

The notice rule

An insurer that charges a premium for a specified coverage must clearly inform you in writing of the limits with respect to the premium charged and whether the coverage from one policy or vehicle may be added to the coverage of another. A policy may also provide reasonable limitations to prevent duplicate payments for the same loss or to prevent adding limits from one policy or from more than one policy from the same company.

A worked example

Suppose you are insured on two cars with $50,000 of UM each, and an uninsured driver causes $250,000 of damages. If the premiums reflect separate limits per car and you were told in writing, UM pays up to $50,000. If they do not, or you were not told, adding the limits may be allowed and UM could pay up to $100,000. Try your own numbers in the Montana UM/UIM stacking calculator.

What to check

Look at your declarations page and the written notice about limits and adding coverage. We did not read Montana court decisions on how these conditions are applied, so ask an attorney. See what section 33-23-203 says and how Montana UM and UIM differ.

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