Question 1

Does New Mexico allow UM/UIM stacking?

Accepted Answer

The statute does not mention it. Court decisions say it is a judicially created doctrine: stacking has been required where separate premiums are charged for UM on each vehicle, and the New Mexico Supreme Court has held that an insurer can limit stacking only with a clear written rejection that explains stacking and discloses the premiums, which it enforced in a July 2025 decision that was not selected for publication when the waiver met those requirements. We read those decisions only in part, so ask an attorney how they apply to your policy.

Question 2

Is underinsured coverage separate in New Mexico?

Accepted Answer

No. Uninsured motorist coverage must include underinsured coverage. An underinsured motorist is one whose liability limits at the time of the accident are less than the limits of your UM coverage (NMSA 66-5-301(B)).

Question 3

Can I reject UM/UIM coverage?

Accepted Answer

Yes, the named insured has the right to reject it, and after a rejection it need not be provided on a renewal unless the insured requests it in writing (66-5-301(C)).

Question 4

How does New Mexico UIM pay?

Accepted Answer

The statute defines when a driver is underinsured but does not say how the payment is calculated, so the calculator shows both an on-top-of-the-other-driver reading and a shortfall-only reading. Your policy wording controls.

Question 5

How long do I have to sue?

Accepted Answer

An injury action must generally be brought within 3 years (NMSA 37-1-8). For minors, the time is extended to one year after the incapacity ends (37-1-10).

New Mexico UM/UIM Stacking Calculator

Estimate your UM/UIM benefits

New Mexico builds underinsured coverage into UM and leaves stacking to the courts and to a signed written rejection

New Mexico UM/UIM Stacking Calculator

Estimate your UM/UIM benefits

New Mexico builds underinsured coverage into UM and leaves stacking to the courts and to a signed written rejection

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