Unmarried Parents Custody in South Dakota: Paternity, Rights, and Filing

The Default Rule: Mother Has Sole Custody

Under SDCL § 25-5-10, when a child is born to unmarried parents in South Dakota, the mother has sole legal and sole physical custody by default. The father has no statutory right to custody or parenting time until he takes legal action — even if his name is on the birth certificate.

This isn't a gender bias in how courts decide custody. It's a jurisdictional starting point: without an established legal parent-child relationship on the father's side, the court has nothing to adjudicate. Once paternity is legally established, both parents stand on equal footing under the best-interests standard.

Step 1: Establish Paternity

A father's first step is establishing legal paternity through one of two paths:

Voluntary Acknowledgment of Paternity. Both parents sign a notarized acknowledgment form, typically offered at the hospital after birth. This creates the legal parent-child relationship and gives the father standing to petition for custody and parenting time. But it does not automatically create a custody or support order — you need a court filing for that.

Paternity action in Circuit Court. If the mother disputes paternity, or if the acknowledgment wasn't signed at the hospital, the father can file a paternity action. The court can order genetic testing to resolve the question. Once paternity is established by the court, the father has the same legal standing as a married father.

Step 2: File for Custody or Parenting Time

With paternity established, the father can file a standalone custody action in Circuit Court using the UJS pro se custody packet. This is separate from a divorce — there's no marriage to dissolve — but the court process is similar:

• File a summons and complaint for custody, along with the financial statement and case filing statement
• Pay the $97 filing fee (or request a fee waiver via Form UJS-022)
• Serve the other parent with the papers and the UJS-302 Parenting Guidelines

The same Fuerstenberg best-interest factors apply. Both parents must complete a court-approved parenting education course within 60 days of service.

Step 3: Custody Decision

The court decides custody under the same best-interests analysis used in divorce cases. Parental fitness, home stability, primary caretaker history, sibling unity, and the child's preference (if age-appropriate) all factor in.

For many unmarried parents, the practical dispute centers on parenting time rather than legal custody. Joint legal custody is common — both parents share major decision-making authority — while one parent holds primary physical custody and the other receives parenting time under the standard guidelines or a custom schedule.

If the parents agree, they can file a stipulation (Form UJS-185) laying out their parenting plan. The court reviews it for compliance with the best-interest standard and typically approves agreements where both parents are reasonable.

Child Support for Unmarried Parents

Child support is calculated the same way regardless of whether the parents were married. South Dakota uses the Income Shares model under SDCL Chapter 25-7, which combines both parents' net incomes and assigns each parent a proportionate share of the child's support obligation.

If a court-ordered parenting plan meets the 180-night shared physical custody threshold and both parents agree in writing to share parenting duties, responsibilities, and expenses in proportion to their incomes, support is calculated using the shared parenting cross-credit formula — the same formula that applies to divorced parents with joint physical custody.

Emergency Situations

If the child is in immediate danger — abuse, neglect, or risk of abduction — an unmarried parent can seek emergency relief. Under SDCL § 25-5-9, a separated or undivorced parent can apply for a Writ of Habeas Corpus to quickly establish physical custody when one parent is withholding the child without a court order. For abuse situations, a Protection Order petition under SDCL Chapter 25-10 can grant temporary custody immediately.

Planning Your Approach

The custody process for unmarried parents follows the same playbook as divorce custody — the main difference is that you're filing a standalone custody action rather than including custody in a divorce complaint, and the father needs to establish paternity first.

The South Dakota Child Custody & Parenting Plan Guide walks through each step for both married and unmarried parents, with specific guidance on the paternity filing process and worksheets for planning your custody proposal.

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