Acknowledgment of Parentage

What is an Acknowledgment of Parentage (AOP) form?

An AOP is a legal form that establishes a parent – child relationship or “parentage.” By filing this form, you add a second parent to a child's birth certificate. Note: Some parents already on a birth certificate through marriage or registered domestic partnership may choose to file an AOP for use outside of Washington State to prove parentage.

Acknowledgment of Parentage form (DOH 422-159) (English) (PDF)

Formulario del Reconocimiento De Paternidad (DOH 422-159) (Spanish) (PDF)

Important note: The Department of Health will accept the prior version of the AOP form only if it was signed before January 1, 2019. The prior form was called the Paternity Acknowledgment form. The non-refundable $18 filing fee must be submitted with the prior form. We will send back all incomplete forms, prior forms that were signed after January 1, 2019 and incorrect payments.

Who can use an AOP form?

You and the mother/birth parent of the child must use the AOP form if any of the following situations apply:

  • If you are the genetic father/parent of the child, but have never married the mother/birth parent.
  • If you are or were married to the mother/birth parent anytime during the pregnancy.
  • If you married the mother/birth parent after the child was born and filed an Assertion.
  • If you lived in the same household with the child for the first 4 years of their life and consider the child as your own.
  • If you and the mother/birth parent conceived the child through assisted reproduction.

An AOP form can only be used if:

  • Everyone agrees, and
  • No other person claims to be a parent of the child.

Who can sign an AOP form?

An AOP must be signed by the mother/birth parent and the second parent of the child.

If there are two parents currently listed on the child's birth certificate, a Denial of Parentage (DOP) form is required to change the second parent. Visit the Denial of Parentage page for more information.

In any other situation, a court order is required to add or remove a parent on a birth certificate. Visit the Court Order page for more information.

Instructions for completing the AOP form

  • Each parent must sign page 1 in the presence of a notary or witness.
  • The notary or witness must sign on page 1.
  • Submit completed AOP with a non-refundable $18 check or money order payable to DOH.
    No payment is required when the parents return this AOP to the hospital within 5 days of birth. The hospital must submit the AOP within 10 days to DOH.
  • If you want to order an updated birth certificate with both parents listed, you must submit a Birth Certificate Order form (DOH 422-182) with a $25 check or money order payable to DOH and a copy the requestor's identification is required.

Mail    In-Person

By Mail

Mailing Address  

Send all forms and payments to:

Department of Health
Center for Health Statistics
PO Box 9709
Olympia, WA 98507

Do I need a notary or a witness?

Yes. Each parent must choose to sign the AOP in front of either a notary OR a witness. The notary or witness must also complete the signature block.

Common notary locations include hospitals, local banks, title companies, and attorneys/county clerks.

A person signing the witnessed statement must be at least 18 years of age and not related by blood or marriage to the individuals who sign an AOP form. The local child support offices will serve as witnesses. Center for Health Statistics staff will not serve as witnesses.

How do I change my child's last name?

You have 1 year from the date the AOP is filed to submit a 422-034 Affidavit for Correction form (PDF) to change your child's last name. You can change it to either parents' names on the AOP (any combination of either parents' first, middle, or last names). You can only make this change once. Both parents listed on the AOP must sign the form. You can send the Affidavit for Correction form separately or together with an AOP form to the Department of Health. There is no additional fee. If the child is 18 years or older, a court order is required to change the child's name.

When would I use an Assertion form?

An Assertion form only applies in situations when a person and the mother/birth parent of the child were married or became state domestic partners after the birth of a child. The spouse can file an Assertion form with the Department of Health. Visit the Assertion page for more information.

What if I change my mind and want to reverse the AOP?

Anyone who signed an AOP or DOP form may change their mind. You can submit a Rescission of Parentage form up to 60 days to undo an AOP or DOP form. Visit the Rescission of Parentage page for more information.

For more information, visit our Frequently Asked Questions page.

Contact us by email

Ordering a certificate with a correction request

  • Send completed certificate order form with your correction request. Include all required documents referenced on the certificate application instruction page.
  • Certificate will be issued after the correction has been processed.

Birth Certificate Application (en español)

Death Certificate Application (en español)

Marriage & Divorce Application (en español)

Exchanging a certificate with a correction request

If you currently have a certified copy of a certificate that was issued less than one year ago, send in the certified copy of the certificate with your correction request; we will exchange the certificate at no charge.