How to modify child custody and parenting time in New Mexico

Sources last checked 8 November 2026. Information only, not legal advice. This page rests on subsection A of NMSA 1978, section 40-4-9.1 (joint custody), as published by FindLaw and current there as of 1 January 2024, and on one opinion of the New Mexico Court of Appeals, Hough v. Brooks (decided 2 March 2017), of which we read the opening paragraph. Read what we could not confirm below.

New Mexico divorce kit Child custody in New Mexico Modifying child support and spousal support in New Mexico After your divorce: changing a support or custody order

The short version

New Mexico requires a change before a court re-sets a custody arrangement. In Hough v. Brooks, the Court of Appeals held that a district court abused its discretion by not finding “a substantial and material change in circumstances” before changing the existing custody arrangement, as required by the Joint Custody Statute, NMSA 1978, 40-4-9.1(A). The court also held that the district court erred by not doing a best-interests analysis and by not considering the statutory factors. So expect two steps: show a substantial and material change, then show the new arrangement is in the child’s best interests. For support instead, see modifying child support and spousal support in New Mexico.

What the statute says

Joint custody in an initial case. Subsection A says there is a presumption that joint custody is in the child’s best interests “in an initial custody determination”.
Changing an existing arrangement. Joint custody is not to be awarded as “a substitute for an existing custody arrangement” unless there has been “a substantial and material change in circumstances” since the prior order that affects the child’s welfare, such that joint custody is presently in the child’s best interests.
Ending joint custody. The court “shall not terminate joint custody” without a substantial and material change in circumstances since the joint custody order, such that joint custody is no longer in the child’s best interests.
Joint custody is not an equal split. The statute says “Joint custody does not imply an equal division of the child’s time” between the parents.
Notice of a move. In a joint custody order, a parent planning to change city or state of residence must give the other parent “thirty days’ notice in writing” stating the date and destination.

What this means in practice

A change is the first gate. A judge who switches custody without finding a substantial and material change risks being reversed, so your filing should explain what changed since the last order.
Best interests still decide. The opinion faults the district court for skipping a best-interests analysis under NMSA 1978, 40-4-9(A) and 40-4-9.1(B).
Evidence matters. The court also says the custody decision was not supported by substantial evidence, so facts you can prove count.

Forms and filing

We did not locate New Mexico’s court forms for modifying custody. The court that entered your decree normally keeps the case, so ask its clerk about forms, fees and local rules. See child custody in New Mexico for more.

What we could not confirm

The rest of the statutes. We read only subsection A of 40-4-9.1 and skimmed the rest of that section’s headings. We did not read NMSA 40-4-9 or the best-interest factors in full. The version we read is FindLaw’s, dated 1 January 2024, so check the New Mexico Legislature or the official compilation for later changes.
The rest of the opinion. We read its first paragraph only, so we cannot describe what counts as a substantial and material change or how the court handles moves.
Later cases. We did not check whether later New Mexico opinions changed the test since 2017.
Procedure. We did not check filing fees, fee waivers, local rules, temporary orders or the jurisdiction act (UCCJEA).

Sources

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