How old do you have to be to adopt in Montana?

In Montana, you must be at least 18 to adopt a child as an unmarried individual or as a legally separated married individual, and an adult to adopt another adult. A married couple adopts jointly. The age rule for children comes from MCA 42-4-402(1) and MCA 42-1-106.

Adopting a child

• An unmarried individual, or a married individual who is legally separated, must be at least 18.
• A married couple adopts together as joint petitioners.
• If you are a stepparent, how these rules apply to your family depends on your marriage and the child's other parent. The District Court clerk in your county, or an attorney, can confirm how they fit your situation.

Adopting an adult

• The person adopting must be an adult. Montana allows an adult to adopt another adult or an emancipated minor, but not the adopter's own spouse.
• Adults may be adopted without their parents' consent. Written consent is required from the adoptee, the adopting person, and the adopter's spouse. The spouse's consent is not needed if the court finds the spouse incapable or withholding consent contrary to best interests, or if the spouse and adopter are legally separated.
• Someone who has adopted an adult may not adopt another adult within 1 year, unless the new adoptee is a sibling of the first.
• The petitioner must have lived in Montana for at least 90 days immediately before filing, and files in the county where a petitioner lives.
• Adult adoptions typically take about 4-8 weeks.

Is there a maximum age or an age gap? Montana's statutes do not give us a specific rule to share on a maximum age or a required age difference between adopter and child. If either is a concern for your family, the District Court clerk in your county or an attorney can confirm it.

The child's age matters too. A child who is 12 or older must consent to the adoption under Mont. Code Ann. § 42-2-301.

Other Montana basics for child adoptions

• Court: Your petition is filed in the District Court. Montana has 56 counties, and the clerk in your county can tell you about local filing details and the current filing fee.
• Residency: For a child adoption there is no minimum residency period under Mont. Code Ann. § 42-1-104(1).
• Home study: The home study requirement is waived for stepparent adoptions under Mont. Code Ann. § 42-4-309.
• Timeline: Stepparent adoptions typically take about 3-6 months.

Situations such as a contested case or an unknown or unlocated parent depend on the specific facts. Talk to the clerk or an attorney about those.

How we help: StepParent Adoption 360 is a document preparation service, not a law firm. You answer questions online, and we prepare the complete court document package for your county. You then file it yourself, without an attorney. The cost is $349 for the first child (or for one adult adoptee) and $99 for each additional child. Your court-ready documents are delivered within 24-48 hours after you finish the questions, and we back them with a 100% court acceptance guarantee. We have helped 151 Montana families, and 34,000+ families nationwide since 2001.