N.M. Admin. Code § 11.3.400.416
It is deemed that two or more employing units are parties to or the subject of a business transfer transaction whenever one such unit acquires an employing enterprise from another such unit, either by merger, consolidation or other form of reorganization; by a contractual or other form of voluntary sale or transfer; or by a transfer by order of court. There is a transfer and an acquisition in this sense, not only where there is an outright sale between separate individuals or concerns, but also where individuals form partnerships or corporations; partnerships form into corporations; new partnerships are formed by the addition or withdrawal of members; a corporation officer or partner acquires the enterprise from the corporation or the partnership; or in any manner that a change is made in the identity or organization of the employing unit. The effective date of such an acquisition and transfer is the date the department determines that the change in ownership or possession and operation is actually consummated as evidenced by a bill of sale, deed to real estate and buildings, a transfer by any other form of written transfer agreement or legally valid instrument, transfer by court order, or by physical or constructive possession.
N.M. Admin. Code § 11.3.400.416