The legal marriage age in Missouri is 18, with no exceptions. Since HB 737 took effect on August 28, 2025, no county recorder may issue a marriage license to anyone under 18, regardless of parental consent, judicial approval, pregnancy, or any other circumstance.1Missouri Revisor of Statutes. Missouri Revised Statutes 451.090 – Issuance of License Prohibited, When – Proof of Age
What the Rule Actually Says
Missouri Revised Statutes Section 451.090 now sets a single, flat age requirement: both applicants must be at least 18. Each must show proof of age with a certified birth certificate, passport, or other government-issued identification, and the recorder must document that proof before issuing the license.1Missouri Revisor of Statutes. Missouri Revised Statutes 451.090 – Issuance of License Prohibited, When – Proof of Age
HB 737, signed by Governor Mike Parson on July 9, 2025, amended Sections 451.040, 451.080, and 451.090 to strip out every previous carve-out that let 16- and 17-year-olds marry.2Missouri Senate. HB 737 – Modifies Provisions Relating to Child Protection Parental consent no longer opens a door. Neither does a court order. The former restriction preventing a spouse over 21 from marrying a minor is gone because the underlying permission is gone.
Getting a Marriage License as an Adult
If both of you are 18 or older, the process is short. You both appear in person at any Missouri county recorder of deeds office with valid photo identification showing your date of birth and a Social Security card.3MO.gov. Marriage and Divorce There is no waiting period, so the license issues the same day you apply.4Greene County Missouri. Marriage Licenses It stays valid for 30 days and can be used anywhere in the state.
Fees vary by county. St. Louis County, for example, charges $48 for a license and keepsake copy. If either of you was previously married, expect to bring documentation showing how that marriage ended, whether a divorce decree or a death certificate.
If One Person Is Under 18
There is no path. A 17-year-old cannot marry in Missouri even with both parents’ written consent and a supportive judge. A pregnant minor cannot marry. A minor engaged to another minor cannot marry. The recorder is prohibited from issuing the license, and no ceremony performed without a valid license produces a legal marriage.
Anyone hoping to marry sooner should wait until the younger partner turns 18. Traveling to another state to marry a Missouri minor is not a workaround worth attempting: crossing state lines with a minor for purposes of criminal sexual activity can trigger federal prosecution under 18 U.S.C. ยง 2423, which carries a minimum of 10 years in prison on conviction.5Office of the Law Revision Counsel. 18 US Code 2423 – Transportation of Minors
Underage Marriages Are Void
If an underage marriage somehow occurs, Missouri law treats it as invalid from the outset. Section 451.020 declares marriages involving persons who lack capacity to marry “presumptively void.”6Missouri Revisor of Statutes. Missouri Revised Statutes 451.020 Because no one under 18 has capacity, the marriage carries no legal weight. A formal annulment proceeding is available but not needed to establish that the marriage was never valid.
The new rule is not retroactive. A marriage that was legally performed under the earlier version of the statute, when 16- and 17-year-olds could marry with parental consent, remains valid. HB 737 controls licenses issued on or after August 28, 2025.
Penalties for Officiants
Anyone who performs a marriage ceremony knowing that one party is under the legal age can be charged under Section 451.115. The offense also covers officiants who solemnize a marriage while aware of any other legal impediment, or who falsely represent that they are authorized to officiate. It is a class C misdemeanor, punishable by up to 15 days in jail and a fine of up to $750.7Missouri Revisor of Statutes. Missouri Revised Statutes 451.115 Depending on the facts, an officiant or other adult involved could also face separate charges under Missouri’s statutory rape laws or federal transportation offenses.
Common Law Marriage
You cannot form a common law marriage in Missouri. Section 451.040 voids them. Living together and holding yourselves out as married does not create a marriage under Missouri law, and it does not offer a way around the age requirement. Missouri courts will, however, recognize a common law marriage that was validly formed in another state if the couple later moves here.