N.M. Code R. § 13.18.2.43
There shall be no provisions excluding or denying a claim for death from pre-existing conditions, except that on insurance written in connection with open-end outstanding balance accounts, a provision will be permitted that excludes or denies a claim resulting from a medical condition for which the debtor received medical diagnosis or treatment within six months immediately preceding the effective date of coverage and which caused or substantially contributed to the death of the insured debtor within 6 months following the effective date of coverage. The effective date of coverage for each part of the insurance attributable to a different advance or charge to the account is the date on which the advance or charge is posted to the account.
N.M. Code R. § 13.18.2.43