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Child Support

When parents separate, each parent is equally responsible for providing for the financial needs of their children. If the parents cannot agree about child support, the court may get involved and make an order for child support. Child support is usually required until the children turn 18 (or 19 if they are still in high school full time).

To get a child support order:

  • Either parent can ask the judge to make a child support order. Or
  • Either parent can go to the local Department of Child Support Services to get help in opening a child support case, paying and collecting child support payments, or enforcing a child support order that was already made in another family law case.

You can also work out an agreement with the other parent. To get help working out an agreement about child support, you can talk to the Family Law Facilitator.

Watch the Finances After Separation's chapter on child support to learn more about child support.

Families Change - Guide to separation & divorce

Click on a topic to learn more:

If you and your child's other parent cannot agree to child support, one of you will have to file papers in court to ask for it. Child support can also be ordered as part of a case filed by the Department of Child Support Services (DCSS). Click on the next topic Help from the San Mateo DCSS.

To ask for a court date, you must have (or must start) one of these types of cases with the other parent of your children:
  • Divorce or legal separation (visit our page for information on divorce & legal separation)
  • Parentage (paternity)
  • Domestic violence restraining order
  • Petition for Custody and Support of Minor Children
  • Child support case with the Department of Child Support Services

If you don't have one of these cases and need to start one, or if you are not sure, talk to the Family Law Facilitator. If you need to respond to child support papers filed by the other parent, do so right away. The Family Law Facilitator can help you.

If you have one of these cases in San Mateo and want to get your first child support order OR want to change an existing order, follow these steps:

  • Fill out a Request for Order (FL-300). You can use the Information Sheet for Request for Order (FL-300-INFO) for information.
    • Also fill out an Income and Expense Declaration (Form FL-150) OR a Financial Statement (Simplified) (Form FL-155).
      • Read Which Financial Form - FL-155 or FL-150? (Form DV-570) to find out if you can use the simpler Form FL-155.

      Self-Prep & File

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        Self-Prep & File

        Click for a computer program that can help you fill out all these forms by answering simple questions.
  • Make at least 2 copies of all your forms.
  • File your forms with the court clerk.
    • If you cannot afford the filing fee, ask for a fee waiver using forms FW-001 and FW-003.
  • Get your court date.
  • Serve your papers on the other parent.
    • Have someone 18 or older, not you, serve the other parent with a copy of your papers. You must also include a blank Responsive Declaration to Request for Order (Form FL-320) and blank Income and Expense Declaration (Form FL-150). Look at the front of Form FL-300 to see if the court ordered you to serve any other documents.
    • If your papers are served in person, they must be served at least 16 court days before your court date.
    • If your papers are served by mail, they must be served at least 16 court days plus 5 regular days before the court date.
    • Personal service is always allowed. But read Information Sheet for Request for Order (FL-300-INFO) to see if you can serve your papers by mail.
    • If the Department of Child Support Services (DCSS) is part of your case, you will also have to serve DCSS.
  • File your Proof of Service.
    • Have the person who served the papers fill out a Proof of Service form: You can use Form FL-330 if the papers were served in person or FL-335 if they were served by mail.
    • Make a copy of the completed Proof of Service and file the original and the copy in the clerk's office.
    • Keep a copy for your records.
  • Go to your court hearing.
    • The judge will use the completed Income and Expense Declarations to figure out guideline child support. Click on the topic 'How is Child Support Calculated' to find out how child support is calculated in California.
      • The Family Law Facilitator can run the child support calculation for you so you know what to expect and can be prepared before you go to court.
    • The judge generally has to order guideline child support. If the parent who has to pay support cannot afford it, they can ask for a hardship deduction. Hardship deductions are very limited and you can only get one in very limited situations.
    • Make sure you get a court order that says how much child support should be paid, when the payments are supposed to start, and whether there is any back child support (called "arrears") owed. If there is back child support owed, find out how much should be paid toward that balance every month, on top of the monthly regular child support.
  • Paying and collecting child support
    • The person ordered to pay child support must start paying according to the court order.
    • If the judge ordered the payments to be taken out of the person's paycheck, a wage assignment must be issued that will then go to that person's employer. The parent ordered to pay is responsible for making payments until the wages start getting garnished (withheld and then paid directly by the employer), which could take a few weeks.
      • The Family Law Facilitator can help you prepare a wage assignment order, called an Order/Notice To Withhold Income For Child Support (FL-195) and explain the process.
    • If you need help collecting the child support payments, you can ask the San Mateo Department of Child Support Services to help. Click on the topic below to find out how to get help from DCSS.

    Find out more about collecting a child support order by going to the California Courts website.


The San Mateo County Department of Child Support Services has free services for all residents of the county to help:

  • Open a child support case, including establishing parentage (paternity) for your children.
  • Get a child support order and help collect the payments.
  • Enforce a child support order (including spousal support if that is a part of your case) made in another family law case.

You can learn more about their services by visiting the San Mateo County Department of Child Support Services website.


California has a statewide formula (called a "guideline") to determine how much child support should be paid.

If the parents cannot agree on an amount, the judge will decide the child support amount based on the guideline calculation.

The guideline calculation mainly takes into account:
  • How much money the parents earn or can earn,
  • How much other income each parent receives (like rental income or unemployment or disability),
  • How many children the parents have together,
  • How much time each parent spends with their children,
  • The tax filing status of each parent,
  • Support of children from other relationships (not counting step-children),
  • Health insurance cost,
  • Mandatory union dues, and
  • Mandatory (not voluntary) retirement contributions.
The child support order may also order the parents to share the costs for:
  • Child care to allow the parent to work or to get training or education for work skills,
  • Children's reasonable health-care expenses,
  • Traveling for visitation from one parent to another,
  • Children's educational needs,
  • Other special needs of the children.

The judge may order something different than the guideline amount in very limited cases. The Family Law Facilitator can help you understand what kinds of cases may be exceptions.

To estimate how much child support the judge may order in your case, go to California Guideline Child Support Calculator. To understand how to fill in the information in the Child Support Calculator, download the User Guide.

  • Keep in mind that using the Calculator on your own can be confusing. If you do not put in the numbers in the right places, you may get the wrong results. So get help from the Family Law Facilitator if you want to make sure your calculations are right.



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