Establishing Paternity in Mercer County, Ohio

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

Mercer County, Ohio · Celina · Probate/Juvenile Division

When parents aren't married, the father establishes his legal rights by first establishing parentage. In Mercer County, parentage and the custody, parenting time, and support that follow are handled by the combined Probate/Juvenile Division (Judge Matthew L. Gilmore, Suite 307).

How do I establish paternity in Mercer County, Ohio?

Paternity can be established three ways: by signing an Acknowledgment of Paternity Affidavit, administratively through the Mercer County CSEA, or by filing a parentage action in the Juvenile Court (R.C. Chapter 3111) — genetic testing can be ordered. File a parentage complaint with the Probate/Juvenile Clerk in Suite 307 with the supporting affidavits, the Parenting Proceeding Affidavit, an Affidavit of Income & Expenses, and a IV-D application, plus the $200 deposit. Once parentage is established, the same court can allocate custody and parenting time and set child support. Until a court orders otherwise, the unmarried mother is the sole residential parent and legal custodian (R.C. 3109.042).

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: Mercer County Court of Common Pleas — General Division (Clerk of Courts, Legal Division)

101 N Main St, Room 205, PO Box 28, Celina, OH 45822
Phone: (419) 586-6461
Hours: Monday 8:30 AM–5:00 PM; Tuesday–Friday 8:30 AM–4:00 PM
Website: www.mercercountyoh.gov/elected-officials/clerk-of-courts/

Juvenile Branch (Never-Married Parents)

Mercer County Court of Common Pleas — Probate/Juvenile Division
101 N Main St, Suite 307, Celina, OH 45822
Phone: (419) 586-1249
Hours: Monday 8:30 AM–5:00 PM; Tuesday–Friday 8:30 AM–4:00 PM

Paternity is the right path if…

This is the right path in Mercer County if…

The parents were never married and you need to legally establish who the father is.
You're a father who wants custody, parenting time, or a say in decisions — which requires establishing parentage first.
You're a mother who needs a support order, which requires legal parentage.
You're willing to file in the Juvenile Court (Suite 307) and, if needed, complete genetic testing.
You understand the unmarried mother is the sole custodian until the court orders otherwise (R.C. 3109.042).

Filing Fees

$200 deposit for a new parentage/custody case in Juvenile Court · $25 stenographer's fee · GAL deposit $1,000 if appointed (contested cases). Confirm current amounts with the Juvenile Court at 419-586-1249.

Forms & Filing Packets

Establish parentage (Juvenile Court) — $200 deposit (new parentage case)

Ohio Supreme Court Standardized Juvenile Forms — Parentage / Custody (index) — The Uniform Juvenile Forms used to establish parentage and allocate parental rights and parenting time when the parents were never married. Mercer's Juvenile Court also publishes its own versions of these forms at mercercountycourts.com.
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.
Mercer County Juvenile Court Forms — The Probate/Juvenile Division's own forms for never-married parents: Complaint for Parentage / Allocation of Parental Rights (Custody) / Parenting Time, parenting plans, motions to change custody or parenting time, motions for contempt with Show Cause Order, financial and health-insurance affidavits, the IV-D application, and the Grandparent Power of Attorney / Caretaker Authorization Affidavit.

Add custody, parenting time, and support — Included in the parentage case deposit

Complaint for Allocation of Parental Rights & Responsibilities (Ohio SC Form 23) — Asks the Juvenile Branch to name a residential parent and legal custodian and set a parenting-time schedule when the parents were never married.
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.
Mercer County Juvenile Court Forms — The Probate/Juvenile Division's own forms for never-married parents: Complaint for Parentage / Allocation of Parental Rights (Custody) / Parenting Time, parenting plans, motions to change custody or parenting time, motions for contempt with Show Cause Order, financial and health-insurance affidavits, the IV-D application, and the Grandparent Power of Attorney / Caretaker Authorization Affidavit.

How to File Paternity in Mercer County

Choose how to establish parentage. Sign an Acknowledgment of Paternity Affidavit, ask the Mercer County CSEA to establish paternity administratively, or file a parentage action in the Juvenile Court. Genetic testing can be ordered if parentage is disputed.
File the parentage complaint. File with the Probate/Juvenile Clerk in Suite 307: the parentage / allocation complaint, proof of paternity if available, the Affidavit of Income & Expenses, the Parenting Proceeding Affidavit and Health Insurance Affidavit, a IV-D application, a Request for Service, and the $200 deposit.
Allocate custody, parenting time, and support. Once parentage is established, the same court can name a residential parent (or approve a shared parenting plan), set parenting time under the Local Rule 7 schedule, and order support using the Ohio worksheet.
Attend the pretrial and hearing. The court can set a pretrial and a final hearing; if the case doesn't settle, it sets a trial. A GAL ($1,000 deposit) may be appointed in a contested case.

Mercer County Practice Notes

Unmarried mother is sole custodian until a court order. Until the Juvenile Court orders otherwise, an unmarried mother is the sole residential parent and legal custodian (R.C. 3109.042). A father establishes his rights by first establishing parentage and then asking the court to allocate parental rights and parenting time.
Parentage drives the timeline. Custody, parenting time, and support can't be ordered for an unmarried father until parentage is established. The fastest path is often an Acknowledgment of Paternity or a CSEA administrative determination; a contested case in Juvenile Court may require genetic testing.
Two courts, two judges named Matthew. Mercer County splits family law between two courts in the same building. The Court of Common Pleas General Division (Judge Matthew K. Fox, Room 301) hears divorce, dissolution, legal separation, annulment, DR post-decree motions, and DVCPOs; cases are filed with the Clerk of Courts (Room 205). The combined Probate/Juvenile Division (Judge Matthew L. Gilmore, Suite 307) hears never-married parentage, custody, parenting time, and support. The same magistrate, Richard M. Delzeith, serves both courts.

Frequently Asked Questions

How is paternity established in Mercer County?: Paternity can be established by an Acknowledgment of Paternity Affidavit, administratively through the CSEA, or by a Juvenile Court parentage action (R.C. Chapter 3111). Genetic testing can be ordered. A new parentage case in Juvenile Court carries a $200 deposit.
Who has custody before a court order if we were never married?: The unmarried mother is the sole residential parent and legal custodian until the Juvenile Court orders otherwise (R.C. 3109.042). The father establishes his rights by first establishing parentage and then asking the court to allocate parental rights and parenting time.
We were never married — where do I file for custody in Mercer County?: In the combined Probate/Juvenile Division (Judge Matthew L. Gilmore) on the 3rd floor, Suite 307, 419-586-1249. Parentage, custody, parenting time, and support for never-married parents are Juvenile Court matters, not divorce-court matters.
How much is a custody, parentage, or support case in Mercer County Juvenile Court?: $200 for a new custody, support, visitation, or paternity case (or to reactivate a closed one, or for a contempt motion) under the Juvenile Local Rules Appendix A (eff. 2026). A relocation notice is $50, and a GAL request requires a $1,000 deposit. Each new or reopened case also carries a $25 stenographer's fee.
How is child support handled in Mercer County?: Support is set under R.C. Chapter 3119 using the Ohio child-support worksheet and is administered by the Mercer County CSEA (220 W. Livingston St., Room B181, 419-586-7961). A IV-D application (DR 10 in DR cases) is required; CSEA collects by wage withholding, distributes payments, and can enforce through license suspension, tax intercept, and contempt referrals.

Free Local Resources in Mercer County

Mercer County Clerk of Courts — Legal Division (divorce, dissolution, legal separation, annulment, CPO). Clerk Calvin Freeman, 101 N. Main St., Room 205, PO Box 28, Celina, OH 45822; (419) 586-6461; fax (419) 586-5826; clerk@mercercountycourts.com. Files all Domestic Relations and civil cases and confirms current deposits (divorce, dissolution, and post-decree motions are each a $350 deposit eff. 4/1/2024). No personal checks — cash, money order, or cashier's check, or pay online via LexisNexis. Court staff cannot give legal advice. Confirm the current amount and any e-filing registration (Common Pleas Loc.R. 29) with the Clerk before filing.
Mercer County Court of Common Pleas — General Division (hears all Domestic Relations cases). Judge Matthew K. Fox, Magistrate Richard M. Delzeith, 101 N. Main St., Room 301, Celina, OH 45822; (419) 586-2122; cpc@mercercountycourts.com. Decides divorce, dissolution, legal separation, annulment, DR post-decree, and domestic-violence civil protection orders. There is no separate Domestic Relations court.
Mercer County Probate/Juvenile Division (never-married parents, non-parent custody). Judge Matthew L. Gilmore, Suite 307 (3rd floor), 101 N. Main St., Celina, OH 45822; juvenile line (419) 586-1249 or (419) 586-2418; fax (419) 586-4506; https://mercercountycourts.com/index.php. Handles parentage, custody, parenting time, and support for never-married parents, plus grandparent and other non-parent custody. New custody/support/visitation/paternity cases carry a $200 deposit (plus a $25 stenographer's fee); confirm current amounts with the court.
Mercer County Child Support Enforcement Agency (CSEA). 220 W. Livingston St., Room B181, PO Box 649, Celina, OH 45822-0649; (419) 586-7961; toll-free 800-207-3597; fax (419) 586-2151; hours M–F 8:30 AM–4:00 PM. Opens IV-D child-support cases, establishes paternity administratively, runs wage withholding, distributes payments, and enforces orders.
A-OK Parenting Program (required for divorce/dissolution with minor children). Mercer County requires each parent in a divorce or dissolution with minor children to attend the A-OK Parenting Program before the final hearing (Common Pleas Loc.R. 21.02). Cost is a one-time $30 per person, paid at the class; you are registered automatically when you file, and the court mails your assigned date. The program runs 6:00–9:00 PM on the 4th Tuesday of January, March, May, July, September, and November in Room 303 of the courthouse. Juvenile (never-married) cases are generally not ordered into A-OK. Call (419) 586-2122 to reschedule.
Ohio Legal Help & legal aid. Ohio Legal Help (https://www.ohiolegalhelp.org/) has plain-English guides and the Ohio Supreme Court standardized forms for divorce, custody, support, and protection orders. Legal Aid of Western Ohio (LAWO) serves Mercer County for income-eligible residents — confirm the current intake line.

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.
Dayton family law — Local attorneys and courts serving the Dayton metro.
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