How to Establish Paternity in Montana
Reviewed by DocDraft Legal Team · Montana · Last updated 2026-09-12
In Montana, establishing paternity means creating the legal father-child relationship so a child gains rights to support, custody and parenting time, health coverage, inheritance, and benefits. Montana follows the Uniform Parentage Act (Title 40, Chapter 6, Part 1). Unmarried parents who agree can sign a paternity acknowledgment form provided by the Department of Public Health and Human Services; once filed it creates a presumption of paternity, and it becomes an irrebuttable finding on the earlier of 60 days or the start of a related court or agency proceeding (Mont. Code Ann. 40-6-105). A child born during a marriage, or within 300 days after it ends, is presumed to be the spouse's child (Mont. Code Ann. 40-6-105(1)(a)), and Montana lets that presumption be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)), a lower bar than the clear and convincing standard most states use. Genetic testing showing a 95 percent or higher probability creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(f)). Timing is load-bearing: where a presumed father exists the action can be brought at any time, but where a child has no presumed father the child must bring the action no later than two years after reaching the age of majority (Mont. Code Ann. 40-6-108). Attorney review of your situation is available through DocDraft.
Find out where you stand in Montana
Where are you in establishing paternity?
DocDraft provides document preparation, not legal advice.
Do I have to go to court to establish paternity in Montana?
No, not if the parents agree. Unmarried parents can establish paternity without court by signing the acknowledgment form provided by the Department of Public Health and Human Services (Mont. Code Ann. 40-6-105(1)(e)). Court is needed only when parents disagree, and the judge can then order genetic testing before ruling.
How long do I have to establish paternity in Montana?
It depends on whether a presumed father exists. An action to declare a presumed father-child relationship can be brought at any time. But a child who has no presumed father must bring the action no later than two years after reaching the age of majority (Mont. Code Ann. 40-6-108).
What is the marital presumption of paternity in Montana?
A child born during a marriage, or within 300 days after the marriage ends, is presumed to be the spouse's child (Mont. Code Ann. 40-6-105(1)(a)). Montana lets that presumption be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)), a lower standard than the clear and convincing evidence many states require.
What genetic-testing result establishes paternity in Montana?
Under Mont. Code Ann. 40-6-105(1)(f), scientific evidence from a paternity test showing a 95 percent or higher statistical probability of paternity creates a presumption that the tested man is the natural father. That presumption is then weighed with other evidence in a court or administrative action.
Montana paternity law at a glance
Montana's Uniform Parentage Act (Title 40, Chapter 6, Part 1) lets unmarried parents skip court: signing a paternity acknowledgment form provided by the Department of Public Health and Human Services creates a presumption of paternity, which becomes an irrebuttable finding on the earlier of 60 days or a related court or agency proceeding (Mont. Code Ann. 40-6-105). Two features set Montana apart. First, the marital presumption for a child born during a marriage, or within 300 days after it ends, can be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)), a lower bar than most states. Second, genetic testing at a 95 percent probability, not the 99 percent some states use, creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(f)). A child with no presumed father has until two years after reaching majority to sue (Mont. Code Ann. 40-6-108).
Establishing Montana paternity for a child born to unmarried parents
Suppose a child is born in Montana to unmarried parents who agree on the father. At the hospital both sign the paternity acknowledgment form provided by the Department of Public Health and Human Services, which once filed creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(e)). If one parent has doubts, they can act within 60 days, because on the earlier of 60 days or a related proceeding the acknowledgment becomes an irrebuttable finding (Mont. Code Ann. 40-6-105(5)). Had the parents disputed parentage, the court could order genetic testing, where a 95 percent or higher probability creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(f)). Had the child been born during a marriage, the spouse would be presumed the parent (Mont. Code Ann. 40-6-105(1)(a)), a presumption Montana lets be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)). Attorney review is available through DocDraft.
Relevant Laws
Mont. Code Ann. 40-6-105 (presumption of paternity)
Provides that a person is presumed to be the natural father when the child is born during the marriage or within 300 days after it ends, and allows that presumption to be rebutted in an appropriate action by a preponderance of the evidence.
Mont. Code Ann. 40-6-105(1)(f) (genetic-testing threshold)
Provides that scientific evidence from a paternity test showing a 95 percent or higher statistical probability of paternity creates a presumption that the tested person is the natural father.
Mont. Code Ann. 40-6-105(1)(e) and (5) (paternity acknowledgment)
Provides that a paternity acknowledgment form provided by the Department of Public Health and Human Services creates a presumption of paternity when filed, and becomes an irrebuttable finding on the earlier of 60 days or the start of a related court or administrative proceeding.
Mont. Code Ann. 40-6-108 (statute of limitations)
Allows an action to declare a presumed father-child relationship at any time, but requires a child with no presumed father to bring the action no later than two years after reaching the age of majority.
Montana Child Support Services Division
The Department of Public Health and Human Services, through its Child Support Services Division, administers the voluntary paternity acknowledgment process and can open a case to establish paternity and support.
42 U.S.C. 666(a)(5) and 45 CFR 303.5 (federal rescission window)
Federal law requires every state child-support program to offer an in-hospital voluntary acknowledgment of paternity with a 60-day window to rescind, after which the acknowledgment can be challenged only for fraud, duress, or material mistake of fact.
Regional Variances
Montana paternity rules at a glance
Voluntary path and form
Unmarried parents establish paternity by signing the acknowledgment form provided by the Department of Public Health and Human Services; once filed it creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(e)).
When the acknowledgment becomes final
A filed acknowledgment becomes an irrebuttable finding of paternity on the earlier of 60 days or the start of a related court or administrative proceeding (Mont. Code Ann. 40-6-105(5)).
Marital presumption and rebuttal standard
A child born during a marriage, or within 300 days after it ends, is presumed to be the spouse's child (Mont. Code Ann. 40-6-105(1)(a)); Montana rebuts that presumption by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)).
Deadline to establish
An action for a presumed father-child relationship can be brought at any time, while a child with no presumed father must sue no later than two years after reaching majority (Mont. Code Ann. 40-6-108).
Genetic-testing threshold
A paternity test showing a 95 percent or higher probability creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(f)), a lower trigger than the 99 percent used in some states.
Who administers it
The Department of Public Health and Human Services and its Child Support Services Division run the acknowledgment process; disputed parentage is decided by the district court, which may order genetic testing.
Suggested Compliance Checklist
Confirm whether a marital presumption applies
Before signing or filing anything days after startingDetermine whether the child was born during a marriage or within 300 days after it ended, which triggers Montana's marital presumption (Mont. Code Ann. 40-6-105(1)(a)). In Montana that presumption can be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)).
Get genetic testing if parentage is uncertain
Before signing an acknowledgment days after startingBecause a filed acknowledgment can harden into an irrebuttable finding, obtain genetic testing first if there is doubt. Under Mont. Code Ann. 40-6-105(1)(f), a result of 95 percent or higher probability creates a presumption of paternity.
Sign and file the paternity acknowledgment
At the hospital or a local office days after startingUnmarried parents who agree sign the acknowledgment form provided by the Department of Public Health and Human Services, which creates a presumption of paternity when filed (Mont. Code Ann. 40-6-105(1)(e)). Keep a copy. Attorney review of your matter is available through DocDraft.
Track the 60-day window before finality
Within 60 days of signing days after startingIf you need to act on a signed acknowledgment, do so before it becomes final on the earlier of 60 days or the start of a court or administrative proceeding about the child (Mont. Code Ann. 40-6-105(5)).
File a parentage action if parents disagree
Any time a dispute arises days after startingIf parents do not agree, file an action to declare the father-child relationship. Where a presumed father exists it can be brought at any time (Mont. Code Ann. 40-6-108). The court can order genetic testing and enter a judgment of parentage.
Keep records and calendar the majority-plus-two-years deadline
Ongoing days after startingSave copies of the acknowledgment, any genetic-test results, and court papers. If the child has no presumed father, calendar the deadline to sue no later than two years after the child reaches the age of majority (Mont. Code Ann. 40-6-108).
| Task | Description | Document | Days after starting |
|---|---|---|---|
| Confirm whether a marital presumption applies | Determine whether the child was born during a marriage or within 300 days after it ended, which triggers Montana's marital presumption (Mont. Code Ann. 40-6-105(1)(a)). In Montana that presumption can be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)). | - | Before signing or filing anything |
| Get genetic testing if parentage is uncertain | Because a filed acknowledgment can harden into an irrebuttable finding, obtain genetic testing first if there is doubt. Under Mont. Code Ann. 40-6-105(1)(f), a result of 95 percent or higher probability creates a presumption of paternity. | - | Before signing an acknowledgment |
| Sign and file the paternity acknowledgment | Unmarried parents who agree sign the acknowledgment form provided by the Department of Public Health and Human Services, which creates a presumption of paternity when filed (Mont. Code Ann. 40-6-105(1)(e)). Keep a copy. Attorney review of your matter is available through DocDraft. | - | At the hospital or a local office |
| Track the 60-day window before finality | If you need to act on a signed acknowledgment, do so before it becomes final on the earlier of 60 days or the start of a court or administrative proceeding about the child (Mont. Code Ann. 40-6-105(5)). | - | Within 60 days of signing |
| File a parentage action if parents disagree | If parents do not agree, file an action to declare the father-child relationship. Where a presumed father exists it can be brought at any time (Mont. Code Ann. 40-6-108). The court can order genetic testing and enter a judgment of parentage. | - | Any time a dispute arises |
| Keep records and calendar the majority-plus-two-years deadline | Save copies of the acknowledgment, any genetic-test results, and court papers. If the child has no presumed father, calendar the deadline to sue no later than two years after the child reaches the age of majority (Mont. Code Ann. 40-6-108). | - | Ongoing |
Frequently Asked Questions
Establishing paternity in Montana means legally identifying a child's father so the child can receive support, custody and parenting time, health coverage, inheritance, and benefits. It can be done by signing a paternity acknowledgment form or through a court action that declares the father-child relationship (Mont. Code Ann. 40-6-105, 40-6-108).
Unmarried parents who agree can sign the paternity acknowledgment form provided by the Department of Public Health and Human Services, which once filed creates a presumption of paternity (Mont. Code Ann. 40-6-105(1)(e)). If parents disagree, a court decides parentage under Mont. Code Ann. 40-6-108, often after ordering genetic testing.
It is a form provided by the Department of Public Health and Human Services that a mother and an alleged father sign to establish paternity without a court order. When filed it creates a presumption of paternity, and it becomes an irrebuttable finding on the earlier of 60 days or a related proceeding (Mont. Code Ann. 40-6-105).
Where a presumed father exists under Mont. Code Ann. 40-6-105(1)(a) to (1)(c), the action can be brought at any time. Where the child has no presumed father, the child must bring the action no later than two years after reaching the age of majority (Mont. Code Ann. 40-6-108).
A child born during a marriage, or within 300 days after it ends, is presumed to be the spouse's child (Mont. Code Ann. 40-6-105(1)(a)). Montana allows that presumption to be rebutted by a preponderance of the evidence (Mont. Code Ann. 40-6-105(3)(a)), often through genetic testing, rather than the higher standard most states use.
Only within a short window. A signed acknowledgment becomes an irrebuttable finding of paternity on the earlier of 60 days after signing or the start of a court or administrative proceeding about the child (Mont. Code Ann. 40-6-105(5)). After that it can be undone only for fraud, duress, or material mistake of fact.
Under Mont. Code Ann. 40-6-105(1)(f), a paternity test showing a 95 percent or higher statistical probability of paternity creates a presumption that the tested man is the natural father. Montana's 95 percent trigger is lower than the 99 percent threshold used in several other states.
The Department of Public Health and Human Services, through its Child Support Services Division, provides the paternity acknowledgment form and can open a case to establish paternity and support. When parentage is disputed, the district court decides it and can order genetic testing (Mont. Code Ann. 40-6-105, 40-6-108).
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