How to Establish Paternity in California
Reviewed by DocDraft Legal Team · California · Last updated 2026-09-12
In California, establishing paternity means legally identifying a child's second parent so the child gains rights to support, custody and visitation, health coverage, inheritance, and benefits. There are two main paths. Unmarried parents who agree can sign a Voluntary Declaration of Parentage, Form CS 909, which once filed with the Department of Child Support Services is equivalent to a judgment of parentage (Cal. Fam. Code 7573). Either parent may cancel it by filing a rescission with the department within 60 days of signing (Cal. Fam. Code 7575). When parents do not agree, or the child was born to a married person, a court action decides parentage. Two California timing rules are load-bearing. An action to declare that a parent-child relationship exists can generally be brought at any time (Cal. Fam. Code 7630), but when the child was born to spouses cohabiting at conception and birth, that conclusive marital presumption (Cal. Fam. Code 7540) can be challenged by genetic testing only if the action is filed and served within two years of the child's birth (Cal. Fam. Code 7541). Attorney review of your situation is available through DocDraft.
Find out where you stand in California
Where are you in establishing paternity?
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What are my options for establishing paternity in California?
There are two routes. Unmarried parents who agree can sign a Voluntary Declaration of Parentage, Form CS 909, and file it with the Department of Child Support Services (Cal. Fam. Code 7573). If parents disagree or the child was born during a marriage, a court decides parentage, often after genetic testing.
How long do I have to establish paternity in California?
An action to declare that a parent-child relationship exists can generally be brought at any time under Cal. Fam. Code 7630. But when the conclusive marital presumption applies, a genetic-testing challenge to it must be filed and served within two years of the child's birth (Cal. Fam. Code 7541).
What is the marital presumption of paternity in California?
Under Cal. Fam. Code 7540, the child of spouses who were living together at conception and birth is conclusively presumed to be a child of the marriage. That presumption can be challenged with genetic testing only in an action filed and served within two years of the child's birth (Cal. Fam. Code 7541).
What genetic-testing result establishes paternity in California?
Under Cal. Fam. Code 7555, genetic testing identifies a person as a genetic parent when the results show at least a 99 percent probability of parentage, using a prior probability of 0.50, and a combined relationship index of at least 100 to 1. A person so identified can rebut only with further genetic testing.
California paternity law at a glance
California lets unmarried parents establish parentage without going to court by signing a Voluntary Declaration of Parentage, Form CS 909. Once filed with the Department of Child Support Services, it is equivalent to a judgment of parentage and lets the second parent be added to the birth certificate (Cal. Fam. Code 7573). Either parent may rescind it by filing with the department within 60 days of signing (Cal. Fam. Code 7575). Two timing rules stand out. An action to declare that a parent-child relationship exists can generally be brought at any time (Cal. Fam. Code 7630). But if the child was born to spouses cohabiting at conception and birth, that conclusive presumption (Cal. Fam. Code 7540) can be challenged by genetic testing only if the action is filed and served within two years of the child's birth (Cal. Fam. Code 7541).
Establishing California paternity for a child born to unmarried parents
Suppose a child is born in California to unmarried parents who agree on the second parent. At the hospital both sign the Voluntary Declaration of Parentage, Form CS 909, filed with the Department of Child Support Services, which is equivalent to a judgment of parentage (Cal. Fam. Code 7573). Weeks later one parent has second thoughts and can still file a rescission with the department within 60 days of signing (Cal. Fam. Code 7575). Had the parents instead disputed parentage, either could ask the court to order genetic testing, where results of at least a 99 percent probability and a 100-to-1 combined relationship index identify a genetic parent (Cal. Fam. Code 7555). Had the child been born during a marriage, a challenge to that conclusive presumption (Cal. Fam. Code 7540) would have to be filed within two years of birth (Cal. Fam. Code 7541). Attorney review is available through DocDraft.
Relevant Laws
Cal. Fam. Code 7540 (conclusive marital presumption of parentage)
Provides that, except as provided in Section 7541, the child of spouses who cohabited at the time of conception and birth is conclusively presumed to be a child of the marriage, subject to a narrow exception for impotence or sterility.
Cal. Fam. Code 7541 (two-year window to challenge the marital presumption)
Allows an action to challenge the parentage of the spouse presumed to be a parent under Section 7540, based on genetic testing, but requires that the action be filed and served not later than two years from the child's date of birth.
Cal. Fam. Code 7573 (effect of a Voluntary Declaration of Parentage)
Provides that a completed voluntary declaration of parentage filed with the Department of Child Support Services is equivalent to a judgment of parentage and confers on the declarant all the rights and duties of a parent.
Cal. Fam. Code 7575 (60-day rescission of a declaration)
Allows either parent to rescind a voluntary declaration of parentage by filing a rescission form with the Department of Child Support Services within 60 days of the date the declaration was signed, unless a court order for custody, visitation, or child support has been entered.
Cal. Fam. Code 7555 (genetic-testing probability threshold)
Provides that genetic testing identifies a person as a genetic parent when the results show at least a 99 percent probability of parentage, using a prior probability of 0.50, and a combined relationship index of at least 100 to 1.
Cal. Fam. Code 7630 (who may bring a parentage action and when)
Sets out who may bring an action to determine the parent-child relationship and provides that an action to declare the existence of a presumed relationship may be brought at any time, while an action to declare its nonexistence must be brought within a reasonable time after learning the relevant facts.
California Department of Child Support Services, Parentage Opportunity Program
The Department of Child Support Services administers the Voluntary Declaration of Parentage (Form CS 909) through its Parentage Opportunity Program, explaining how unmarried parents establish parentage and how the declaration is signed and filed.
Regional Variances
California paternity rules at a glance
Voluntary path and form
Unmarried parents establish parentage by signing the Voluntary Declaration of Parentage, Form CS 909, filed with the Department of Child Support Services. Once filed it is equivalent to a judgment of parentage (Cal. Fam. Code 7573).
Rescission window
Either parent may rescind a signed declaration by filing with the Department of Child Support Services within 60 days, unless a custody, visitation, or support order has been entered (Cal. Fam. Code 7575).
Marital presumption and deadline
A child of spouses cohabiting at conception and birth is conclusively presumed a child of the marriage (Cal. Fam. Code 7540); a genetic-testing challenge must be filed and served within two years of birth (Cal. Fam. Code 7541).
Deadline to establish
An action to declare that a parent-child relationship exists can generally be brought at any time (Cal. Fam. Code 7630), so there is no fixed statute of limitations to establish parentage where no conclusive presumption applies.
Genetic-testing threshold
Genetic testing identifies a genetic parent at a 99 percent probability of parentage, using a prior probability of 0.50, with a combined relationship index of at least 100 to 1 (Cal. Fam. Code 7555).
Who administers it
The California Department of Child Support Services runs the Voluntary Declaration of Parentage program and can open a case; disputed parentage is decided by the superior court, which may order genetic testing.
Suggested Compliance Checklist
Confirm whether a marital presumption applies
Before signing or filing anything days after startingDetermine whether the child was born to spouses cohabiting at conception and birth, which triggers California's conclusive marital presumption (Cal. Fam. Code 7540). If it applies, a genetic-testing challenge must be filed and served within two years of the child's birth (Cal. Fam. Code 7541).
Get genetic testing if biological parentage is uncertain
Before signing a declaration days after startingBecause a signed declaration has the force of a judgment, obtain genetic testing first if there is any doubt. Under Cal. Fam. Code 7555, results of at least a 99 percent probability and a combined relationship index of at least 100 to 1 identify a genetic parent.
Sign and file the Voluntary Declaration of Parentage
At the hospital or a local office days after startingUnmarried parents who agree sign Form CS 909 and file it with the Department of Child Support Services, which is equivalent to a judgment of parentage (Cal. Fam. Code 7573). Keep a copy. Attorney review of your paternity matter is available through DocDraft.
Track the 60-day rescission window
Within 60 days of signing days after startingIf you need to cancel a signed declaration, file a rescission form with the Department of Child Support Services within 60 days of the date it was signed, unless a custody, visitation, or support order has been entered (Cal. Fam. Code 7575).
File a parentage action if parents disagree
Any time a dispute arises days after startingIf parents do not agree, ask the Department of Child Support Services to open a case or file a petition to determine the parent-child relationship in the superior court (Cal. Fam. Code 7630). The court can order genetic testing and enter a judgment of parentage.
Keep records of the declaration, testing, and orders
Ongoing days after startingSave copies of the signed declaration, any genetic-test results, and court papers, and calendar the 60-day rescission window and the two-year marital-presumption challenge deadline (Cal. Fam. Code 7541) so you do not miss a right-forfeiting date.
| Task | Description | Document | Days after starting |
|---|---|---|---|
| Confirm whether a marital presumption applies | Determine whether the child was born to spouses cohabiting at conception and birth, which triggers California's conclusive marital presumption (Cal. Fam. Code 7540). If it applies, a genetic-testing challenge must be filed and served within two years of the child's birth (Cal. Fam. Code 7541). | - | Before signing or filing anything |
| Get genetic testing if biological parentage is uncertain | Because a signed declaration has the force of a judgment, obtain genetic testing first if there is any doubt. Under Cal. Fam. Code 7555, results of at least a 99 percent probability and a combined relationship index of at least 100 to 1 identify a genetic parent. | - | Before signing a declaration |
| Sign and file the Voluntary Declaration of Parentage | Unmarried parents who agree sign Form CS 909 and file it with the Department of Child Support Services, which is equivalent to a judgment of parentage (Cal. Fam. Code 7573). Keep a copy. Attorney review of your paternity matter is available through DocDraft. | - | At the hospital or a local office |
| Track the 60-day rescission window | If you need to cancel a signed declaration, file a rescission form with the Department of Child Support Services within 60 days of the date it was signed, unless a custody, visitation, or support order has been entered (Cal. Fam. Code 7575). | - | Within 60 days of signing |
| File a parentage action if parents disagree | If parents do not agree, ask the Department of Child Support Services to open a case or file a petition to determine the parent-child relationship in the superior court (Cal. Fam. Code 7630). The court can order genetic testing and enter a judgment of parentage. | - | Any time a dispute arises |
| Keep records of the declaration, testing, and orders | Save copies of the signed declaration, any genetic-test results, and court papers, and calendar the 60-day rescission window and the two-year marital-presumption challenge deadline (Cal. Fam. Code 7541) so you do not miss a right-forfeiting date. | - | Ongoing |
Frequently Asked Questions
Establishing paternity in California means legally identifying a child's second parent so the child can receive support, custody and visitation, health coverage, inheritance, and benefits. It can be done by signing a Voluntary Declaration of Parentage or through a court action that determines the parent-child relationship (Cal. Fam. Code 7573, 7630).
Unmarried parents who agree can sign a Voluntary Declaration of Parentage, Form CS 909, and file it with the Department of Child Support Services, which is equivalent to a judgment of parentage (Cal. Fam. Code 7573). If parents disagree, a court determines parentage under Cal. Fam. Code 7630, often after ordering genetic testing.
It is a form, Form CS 909, that unmarried parents sign to establish a legal parent-child relationship without going to court. Once filed with the Department of Child Support Services it is equivalent to a judgment of parentage and confers on the signer all rights and duties of a parent (Cal. Fam. Code 7573).
When spouses cohabited at conception and birth, the child is conclusively presumed a child of the marriage (Cal. Fam. Code 7540). An action to challenge that presumption by genetic testing must be filed and served no later than two years from the child's date of birth (Cal. Fam. Code 7541).
An action to declare that a parent-child relationship exists can generally be brought at any time (Cal. Fam. Code 7630). The main hard deadline is the two-year window to challenge the conclusive marital presumption by genetic testing (Cal. Fam. Code 7541), plus the 60-day window to rescind a signed declaration (Cal. Fam. Code 7575).
Yes, within a limited window. Either parent may rescind a signed Voluntary Declaration of Parentage by filing a rescission form with the Department of Child Support Services within 60 days of the date it was signed, unless a court order for custody, visitation, or child support has already been entered (Cal. Fam. Code 7575).
Under Cal. Fam. Code 7555, genetic testing identifies a person as a genetic parent when the results show at least a 99 percent probability of parentage, using a prior probability of 0.50, and a combined relationship index of at least 100 to 1. That identification can be rebutted only by further genetic testing.
The California Department of Child Support Services administers the Voluntary Declaration of Parentage program and can open a case to establish parentage and support. When parentage is disputed, the superior court decides it and can order genetic testing before entering a judgment (Cal. Fam. Code 7573, 7630).
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