Marital Settlement Agreements in Montana

A marital settlement agreement is the written contract in which divorcing spouses set their own terms for property, debts, maintenance, and their children. Montana's statute calls it a separation agreement, and one section of the code, MCA § 40-4-201, governs what it may contain, how far it binds a judge, and how it is enforced. This page walks through that section. It is part of our Montana Divorce Guide.

What Montana Law Calls It and What It Can Cover

The statute says that, "to promote amicable settlement of disputes," spouses may enter into a written separation agreement containing provisions for "disposition of any property owned by either of them, maintenance of either of them, and support, parenting, and parental contact with their children" (MCA § 40-4-201(1)). Where children are involved, the agreement may contain the parenting plan that MCA § 40-4-234 requires.

In practice a complete agreement also assigns debts. The statute that lets a court enter a decree without a hearing lists what the filed agreement should address: disposition of property, distribution of debts, maintenance of either party, and support, parenting, and parental contact with any minor children (MCA § 40-4-108(4)(b)(ii)(C)). Our guide to agreeing on everything before you file covers each piece.

Which Terms Bind the Judge

This is the heart of the statute. A separation agreement is not a request the judge may freely rewrite, and it is not a private contract the judge must rubber-stamp. The answer depends on the subject.

The reason for the split is that children are not parties to their parents' contract. The court must determine a parenting plan "in accordance with the best interest of the child" (MCA § 40-4-212(1)). For child support, the guidelines "must be used in all cases," including those in which the parties have agreed on an amount, and if an agreed amount varies from the guideline figure the court must state reasons (MCA § 40-4-204(3)(a) and (b)). See whether parents can agree to no child support.

The Unconscionability Review

For property and maintenance, the court looks at "the economic circumstances of the parties and any other relevant evidence produced by the parties" and decides whether the agreement is unconscionable (MCA § 40-4-201(2)). The statute does not define the word. Montana courts have interpreted it case by case, and the outcome turns on the facts: what each spouse received, what each knew, and the conditions under which the agreement was signed.

If the court finds the agreement unconscionable, it has two choices. It "may request that the parties submit a revised separation agreement or it may make orders for the disposition of property, maintenance, and support" (MCA § 40-4-201(3)). An agreement that is uneven is not automatically unconscionable. Montana law requires an equitable division, not an equal one, and spouses may have sound reasons for the trade they made.

Disclosure Comes Before Signing

A settlement is only as sound as the information behind it. Montana requires each spouse to serve a final declaration of disclosureand a current income and expense declaration, signed under penalty of perjury, "before or at the time that the parties enter into an agreement for the resolution of property or support issues" (MCA § 40-4-253(1)(a)(i)). Absent good cause, the court may not enter a judgment on property rights unless each party has executed and served those documents (MCA § 40-4-254).

The consequences of leaving something out are written into the code. An asset or liability omitted from the final declaration is presumed to be grounds for awarding the undisclosed asset to the other spouse, or the undisclosed liability to the spouse who hid it (MCA § 40-4-253(4)). And the separation agreement statute says a decree may be modified under the disclosure statutes "for failure to disclose assets and liabilities" (MCA § 40-4-201(7)). Our financial disclosure guide explains the declarations.

From Agreement to Decree

If the court finds the agreement not unconscionable as to property and maintenance and "not unsatisfactory as to support," one of two things happens (MCA § 40-4-201(4)):

• Unless the agreement says otherwise, its terms are set forth in the decree and the parties are ordered to perform them.
• If the agreement provides that its terms are not to be set forth in the decree, the decree identifies the agreement and states that the court found its terms not unconscionable.

The choice matters for enforcement, as the next section explains. It is a drafting decision to make deliberately, not by default.

Enforcement: Judgment and Contract

Terms of the agreement set forth in the decree "are enforceable by all remedies available for enforcement of a judgment, including contempt, and are enforceable as contract terms" (MCA § 40-4-201(5)). That gives a former spouse two sets of tools: the court's power to enforce its own orders, and ordinary contract remedies.

The statute speaks only of terms set forth in the decree. It does not say what remedies apply to terms the spouses chose to keep out of the decree, which is one reason that choice deserves advice from a lawyer.

Changing the Agreement Later

By default, terms set forth in the decree "are automatically modified by modification of the decree." The agreement can change that default for some terms. If the agreement so provides, the decree may "expressly preclude or limit modification" of its terms, except terms concerning the support, parenting, or parental contact with the children (MCA § 40-4-201(6)).

So spouses can agree that maintenance will not be modified, but they cannot agree to put child support or the parenting plan beyond the court's reach. A clause like that has long-term consequences for both the paying and the receiving spouse. Our property division and maintenance pages describe the underlying law.

This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.