Missouri Child Marriage Laws: Age 18 Floor and Past Rules

The minimum marriage age in Missouri is 18, with no exceptions for parental consent or a court order. The rule took effect August 28, 2025, when House Bill 737 amended RSMo 451.090 to bar any recorder in the state from issuing a marriage license to anyone under 18.1Missouri Revisor of Statutes. Missouri Code 451.090 – Issuance of License Prohibited, When – Proof of Age

An Absolute Floor at 18

Both applicants must be at least 18. No parent, guardian, or judge can authorize a marriage involving a minor in Missouri. The recorder is also required to note on every license whether the applicants are of legal age and to document proof through a certified birth certificate, passport, or other government-issued identification.1Missouri Revisor of Statutes. Missouri Code 451.090 – Issuance of License Prohibited, When – Proof of Age

What the Law Used to Allow

If you have heard that teenagers can marry in Missouri with parental permission, that information is out of date. Under the previous framework, 16- and 17-year-olds could marry with written consent from a parent or guardian, and children under 15 could marry if a judge found that unusual conditions made the marriage advisable. HB 737 stripped away every one of those exceptions.2Dunklin County. Changes to Age Requirements to Apply for a Marriage License in the State of Missouri

Marriages that were legally entered into before August 28, 2025 are not retroactively invalidated. The new rule applies only to license applications going forward.

Getting a License Once You Are 18

Both applicants appear together, in person, at a County Recorder of Deeds office. There is one exception to the in-person requirement: an applicant who is incarcerated or on active military duty outside the state can submit a notarized affidavit instead.3Missouri Revisor of Statutes. Missouri Code 451.040 – Marriage License Requirements

Each applicant brings:

If either applicant was previously married, you will need the date that marriage ended.

Missouri has no residency requirement for a marriage license, so you do not need to live in the state to marry here.5Morgan County, Missouri. Marriage License There is also no waiting period; the license is issued at the time of application once everything checks out.

Fees vary by county. Boone County charges $51, and the City of St. Louis charges $60, which includes a certificate copy fee.6Boone County, Missouri. Marriage License Filing Requirements in Boone County, Missouri7City of St. Louis. Apply for a Marriage License – City of St. Louis Most offices accept cash and credit or debit cards, though cards sometimes carry a small service charge.

Once issued, the license is valid for 30 days.8Missouri Revisor of Statutes. Missouri Code 451.040 – Marriage License Requirements If you do not hold your ceremony in that window, the license expires and you start over with a new application and fee. The ceremony must take place within Missouri; a license issued here is not valid in another state.6Boone County, Missouri. Marriage License Filing Requirements in Boone County, Missouri

Other Marriages Missouri Does Not Allow

Age is not the only restriction. Under RSMo 451.020, marriages between close relatives are presumptively void. That covers marriages between parents and children at any generational level, siblings of half or full blood, aunts and nephews, uncles and nieces, and first cousins. The same statute voids marriages where either person lacks the capacity to enter into a marriage contract, unless a court with jurisdiction approves the union.9Missouri Revisor of Statutes. Missouri Code 451.020 – Prohibited Marriages