Uninsured Motorist Coverage in New Mexico: Stacking, Limits, and Your Rights

What UM and UIM Coverage Actually Do in New Mexico

Uninsured motorist (UM) coverage pays for your injuries when the driver who hit you has no insurance at all. Underinsured motorist (UIM) coverage steps in when the at-fault driver has insurance, but the limits are too low to cover your actual damages. Both coverages come from your own policy, and both matter in New Mexico, where a meaningful share of drivers carry no insurance.

New Mexico law requires insurers to offer UM/UIM coverage to every policyholder. Under NMSA 1978 § 66-5-301.1, insurers must offer UM coverage in limits at least equal to the insured’s liability limits. A policyholder can reject UM/UIM coverage, but that rejection must be in writing. If you never signed a written rejection, your insurer may be required to provide coverage even if it was not listed on your declarations page.

New Mexico’s minimum liability limits are $25,000 per person, $50,000 per accident for bodily injury, and $10,000 for property damage, under NMSA 1978 § 66-5-301. These minimums are thin. A serious injury can exhaust a $25,000 per-person BI policy before accounting for surgery, rehabilitation, or lost wages. That is exactly the scenario where your own UM/UIM coverage becomes the primary financial protection you have.

How UIM coverage works in practice: if the at-fault driver carries $25,000 in liability coverage and your damages are $80,000, their policy pays its $25,000 limit first. Your UIM coverage then covers the gap, up to your own policy’s UIM limit. The at-fault driver’s policy acts as a floor; your policy covers the ceiling.

Stacking UM Coverage Across Multiple Vehicles

Stacking refers to combining the UM/UIM limits from multiple vehicles or multiple policies to reach a higher total available coverage. New Mexico has historically recognized and permitted stacking, but the rules are not simple, and insurers regularly try to limit it.

Intra-policy stacking: if you have two or three vehicles on the same policy, each with $25,000 in UM/UIM coverage, stacking allows you to combine those limits to reach $50,000 or $75,000 total. This applies when a single crash injures a policyholder who is covered under multiple vehicles on the same policy.

Inter-policy stacking: when you and another household member each have separate policies, and both apply to the same accident, New Mexico courts have in various circumstances allowed stacking across those separate policies as well. Insurance companies frequently include anti-stacking clauses in their policies. New Mexico courts have sometimes struck down these clauses as contrary to the purpose of the UM/UIM statutes, but not uniformly. The result is that whether stacking is available in your specific situation depends on how your policy is written and how recent New Mexico case law has addressed that language.

This is one area where having an attorney review your policy before you accept a settlement figure matters. An insurer will not voluntarily calculate and offer you the stacked limit. They will offer you the single-vehicle limit and hope you do not know the difference.

What Happens When the At-Fault Driver Has No Insurance in NM

When the driver who hit you carries no insurance, the path to compensation runs through your own UM coverage. You file a claim with your own insurer, and the insurer steps into the role the at-fault driver’s insurer would have occupied.

The procedural catch is that your insurer is now representing its own financial interest against you, even though you are its own policyholder. Your insurer has an incentive to pay as little as possible on your UM claim, the same incentive the other driver’s insurer would have had. This is not paranoia; it is how UM claims are administered.

Under New Mexico law, your insurer owes you a duty of good faith in handling the UM claim. Unreasonable delay, lowballing, or misrepresenting your coverage rights can give rise to a bad faith claim against your own insurer, which carries potential for damages beyond the policy limits.

One specific tactic to watch for: some insurers appoint the same attorney to investigate the at-fault driver’s conduct and to defend the insurer’s position on the UM claim. This creates a potential conflict of interest that is worth identifying and raising if it occurs in your case.

When Your Insurer Tries to Lowball Your UM Claim

The most common point of dispute in UM/UIM claims is the valuation of your damages. Your insurer’s adjuster will assign a number to your injuries, and that number will almost always be lower than what a jury would award or what your claim is actually worth.

Factors your insurer is likely to minimize include: the long-term impact of your injuries (particularly soft tissue injuries that are expensive to treat but difficult to visualize), lost income and reduced earning capacity, pain and suffering, and future medical costs. These are the exact categories where adjuster valuations diverge most sharply from real-world damages.

If your insurer denies your UM claim or offers a figure you believe is unreasonably low, the next step depends on what your policy says. Many UM policies in New Mexico include an arbitration clause, which requires disputed claims to go to arbitration rather than court. Whether you can demand arbitration if the insurer refuses to pay or offers an unacceptable amount varies by policy language. An attorney can review your policy, identify whether arbitration is available and beneficial, and pursue that process on your behalf.

The statute of limitations under NMSA 1978 § 37-1-8 is three years from the date of the accident for personal injury claims in New Mexico. However, your insurance policy may include notice provisions that require you to report a potential UM claim within a much shorter period. Reading your policy promptly after a crash, and calling an attorney if the at-fault driver is uninsured, are both steps that protect your position.

If the insurer denies the claim outright, you have the right to pursue it through legal action. The insurer cannot simply say no and close the file. The denial triggers rights, including the right to challenge the denial and, in appropriate cases, to pursue a bad faith claim if the denial was unreasonable.