Establishing Paternity in Union County

Reviewed by Stephanie Green · Managing Partner & Co-Founder · Last updated June 11, 2026

Union County, Ohio · Marysville

When parents were never married, the Union County Juvenile Court (Room 107, before Judge Rodger) handles parentage, custody, parenting time, and support. In Ohio, the mother of a child born outside marriage is the only legal custodian until a court says otherwise, so an unmarried father usually has to prove he is the father first — the court suggests asking the Child Support Enforcement Agency to decide paternity before you file.

How do I establish paternity in Union County, Ohio?

File a Complaint to Establish Paternity (plus a request to set custody and parenting time) in the Union County Juvenile Court, Room 107, (937) 645-3029 ext. 3411, along with the Parenting Proceeding Affidavit and, where support is at issue, the Health Insurance Affidavit and a Title IV-D Application. An agreed case costs $75 to file; a contested case costs $115. Paternity can be established by an Acknowledgment of Paternity, a prior judgment, or genetic testing. The court suggests asking CSEA at (937) 644-1010 to decide paternity before you file.

Ohio Custody by the Numbers

Best interest The single standard that governs every Ohio custody decision Source: Ohio Revised Code § 3109.04
No set age There is no age a child can choose a parent — the judge weighs a mature child's wishes Source: Ohio Revised Code § 3109.04(B)
Change in circumstances Required, plus a best-interest finding, before the residential parent can be changed Source: Ohio Revised Code § 3109.04(E)(1)
Shared parenting Either parent may ask the court for a joint parenting plan Source: Ohio Revised Code § 3109.04(G)

Compare Types of Custody in Ohio

Custody type	Who makes major decisions	Where the child lives	Best when
Shared parenting	Both parents jointly, under a written plan	Time is split per the plan (not always 50/50)	Parents can communicate and cooperate on decisions
Sole legal & residential	One parent	Primarily with that parent	One parent is unable or unwilling to co-parent
Split custody	Each parent for the child in their care	Siblings are divided between the two homes	Rare — only when it serves each child's best interest
Legal custody to a non-parent	The relative or caregiver granted custody	With the non-parent caregiver	Neither parent can safely care for the child

Where to File: Union County Court of Common Pleas - Domestic Relations Division

215 W 5th St, Marysville, OH 43040, Marysville, OH 43040
Phone: (937) 645-3015
Hours: Monday–Friday (call the Clerk to confirm current hours)
Website: www.unioncountyohio.gov/departments/CommonPleasCourt

Paternity is the right path if…

You and the other parent were never married to each other.
You need to legally establish the father (by acknowledgment, judgment, or genetic testing).
You want a custody, parenting-time, or child-support order you can enforce.
Ohio is the children's home state under the UCCJEA (lived in Ohio about the last 6 months).

Filing Fees

Agreed custody case $75 · contested $115 · register an out-of-state order $115 ($175 with enforce/modify) · show-cause motion $100 · confirm amounts with the Juvenile Court at (937) 645-3029

Forms & Filing Packets

Establish parentage and allocate custody — $75 agreed · $115 contested

File in the Union County Juvenile Court with the UCCJEA Parenting Proceeding Affidavit.

Complaint to Establish Paternity (with custody & parenting time) — Filed in the Union County Juvenile Court to legally establish the father and ask the court to set custody and parenting time. Union uses the Ohio Supreme Court standardized juvenile forms.
Parenting Proceeding Affidavit (UCCJEA · R.C. 3127.23) — Lists where each child has lived for the last 5 years and with whom, confirming Ohio's jurisdiction over custody under the UCCJEA. Required in any case involving minor children.

Add a child-support order — Included with the Juvenile case

Include the official worksheet, the Health Insurance Affidavit, and a IV-D application so CSEA can calculate and enforce support.

Ohio Child Support Computation Worksheet (2024 Income Shares) — Run the official Ohio Child Support Calculator, print, and sign. Required any time you ask the court to set or change support.
Health Insurance Affidavit (Ohio SC Affidavit 4) — Discloses whether health insurance is available for the children through either parent's employer, so the court can order medical support.
Title IV-D Child Support Services Application — Opens a IV-D child-support case with the Union County Child Support Enforcement Agency so it can calculate, collect, and enforce support by wage withholding. Available from the Juvenile Clerk or CSEA at (937) 644-1010; confirm the current form before filing.

How to File Paternity in Union County

Confirm Juvenile Court is the right court. Never-married parents file parentage, custody, and support in the Union County Juvenile Court, Room 107, not the Domestic Relations docket.
Establish paternity. Paternity is set by an Acknowledgment of Paternity, a prior judgment, or genetic testing; the court suggests asking CSEA at (937) 644-1010 to decide it first.
Prepare the complaint. File a Complaint to Establish Paternity plus a request to set custody and parenting time, with the UCCJEA Parenting Proceeding Affidavit.
Add support forms if needed. Where support is at issue, add the Health Insurance Affidavit, the worksheet, and a Title IV-D Application.
File and attend the hearing. File at the Juvenile Court ($75 agreed / $115 contested). The court allocates parental rights and applies its standard parenting-time guidelines.

Union County Practice Notes

Mother is the default custodian until a court orders otherwise. In Ohio, the mother of a child born outside marriage is the only legal custodian until a court says otherwise. An unmarried father generally needs both established parentage and a custody or parenting-time order before his rights are enforceable.
The court suggests letting CSEA decide paternity first. Union's Juvenile Court suggests asking the Child Support Enforcement Agency to decide paternity before you file your custody case. Once parentage is established, the court can allocate custody, parenting time, and support.
Best-interest standard governs. R.C. 3109.04(F)(1) lists 10+ factors: each parent's wishes, the child's wishes (when of sufficient age), the child's interaction with parents/siblings, adjustment to home/school/community, mental and physical health of all involved, the parent more likely to facilitate court-approved parenting time, child support compliance, criminal history, residence outside Ohio, and any history of abuse.

Frequently Asked Questions

Do unmarried fathers have custody rights in Union County?: Not automatically. In Ohio, the mother of a child born outside marriage is the only legal custodian until a court says otherwise, so a father usually has to prove he is the father first. The court suggests asking the Child Support Enforcement Agency to decide paternity before you file. Once parentage is established in the Union County Juvenile Court, the court can allocate custody and parenting time.
What does it cost to file for custody in the Union County Juvenile Court?: An agreed custody case costs $75 to file in the Union County Juvenile Court (Room 107, (937) 645-3029 ext. 3411); a contested one costs $115. A show-cause motion to enforce an order has a $100 deposit. Registering an out-of-state custody order is $115, or $175 if you also ask to enforce or modify it at the same time.
What is a IV-D application and why do I need one?: A IV-D Application opens a child-support case with your county's Child Support Enforcement Agency (CSEA). Once opened, CSEA collects support through automatic wage withholding, distributes it to the receiving parent, and can enforce the order through license suspension, federal tax intercept, credit reporting, and contempt referrals. Filing a IV-D Application is standard whenever a child-support order is issued.
What does it mean for Ohio to be my child's 'home state' under the UCCJEA?: Under the UCCJEA (R.C. 3127), Ohio is the children's home state when they have lived in Ohio with a parent for at least 6 consecutive months immediately before the filing. If the children recently moved, the prior state may still have jurisdiction. Ohio courts can also decline jurisdiction as an inconvenient forum under R.C. 3127.21 even when home-state requirements are met.

Free Local Resources in Union County

Union County Clerk of Courts. Provides current filing fees, local forms, and filing instructions for custody, divorce, and dissolution cases. Call (937) 645-3015 or visit https://www.unioncountyohio.gov/departments/CommonPleasCourt before filing to confirm deposits and packet requirements.
Union County Child Support Enforcement Agency (CSEA). Union County's IV-D agency opens child-support cases, runs wage withholding, distributes payments, and enforces orders. File a IV-D Application when establishing or modifying support.

Related to your paternity case

Child Support — Calculate, establish, or modify support under Ohio's guidelines.
Grandparents' Rights — Seek visitation or custody when it serves the child's best interest.
Post-Decree Modification — Update custody, support, or parenting orders after your case ends.

Related guides

In-depth, attorney-written guides on paternity and related Ohio family law topics.

Fathers' Rights in Ohio: Custody, Paternity, and Parenting Time — Ohio law does not favor mothers over fathers — but unmarried fathers must establish paternity before they have any rights. Here's how fathers protect their relationship with their children.
Ohio Child Custody Laws: What Every Parent Should Know — Ohio custody law turns on one principle: the best interest of the child. This guide explains sole custody, shared parenting, the statutory factors, and how courts decide.
Child Support Calculation in Ohio: How the Formula Works — Ohio calculates child support with the income shares model, combining both parents' incomes to set a shared obligation. Here's how the formula works and what changes the bottom line.

Keep exploring

Ohio Paternity guide — Statewide overview of paternity in Ohio.
Columbus family law — Local attorneys and courts serving the Columbus metro.
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