If your income has changed and you are trying to understand how child support actually gets set or changed in California, it might be challenging to understand the whole process at once. This post lays out the whole process, from the first order through a later modification. It is not legal advice. It points to the official state resources at each step so you can read the rules yourself and find the free help that exists along the way or decide to consult an attorney.

The short version: child support is set when a court issues an order, usually as part of a divorce or parentage case, and it stays in force until a court changes it. A modification is not a separate kind of case. It is the same machinery run a second time, triggered by something that changed.

Two ways a case can run

Before the steps, one important distinction matters, because it changes which website and which instructions apply to you:

  1. A family law case in court. You (or you and the other parent) handle the case directly through the superior court. Child support is one of the orders decided inside a divorce, legal separation, or parentage case. The official guide lives at the California Courts child support self-help center.

  2. A case with the Local Child Support Agency (LCSA / DCSS). A government agency, the California Department of Child Support Services, opens and manages the case for you. This is free, and either parent can ask for it. Here is how a DCSS case works and how to open a case. If a child receives certain public benefits, a case is opened automatically.

The steps below are similar in both tracks, but the forms and instructions slightly differ. When you have an agency case, follow the court’s instructions for an LCSA case rather than the standard ones.

The procedure: how an order gets set

Step 1. The case exists. Child support gets decided inside an existing case, normally a divorce or a parentage case. If there is no case yet, one has to be opened, either through the court or by starting a case with the LCSA.

Step 2. Both incomes go on the record. Each parent files an Income and Expense Declaration (form FL-150). This is the financial backbone of the calculation. The guideline number reads its income figures straight off this form.

Step 3. The guideline formula runs. California support comes from a formula written into Family Code section 4055. It uses both parents’ income, the timeshare, the number of children, and certain deductions. It is public law. You can see your own estimate first with the SupportSplit calculator, and the post on estimating support without paying for software explains the five inputs.

Step 4. A judge issues the order. If the parents agree on a number, they can submit a written agreement, the Stipulation to Establish or Modify Child Support (form FL-350), for a judge to sign. If they do not agree, the matter is decided at a hearing after a parent submits a written request (FL-300). Either way, the result is a court order with a specific dollar amount.

Step 5. Payments are collected. By default, every California support order includes a wage assignment, an income withholding order sent to the employer, under Family Code section 5230. That assignment can be stayed under Family Code section 5260, so when the parents agree in writing to another arrangement, some pay each other directly instead (via Zelle, check, or bank wire). The self-help center explains how to update an income withholding order when things change.

How an order gets changed or modified

A modification follows the same shape, with one extra requirement at the front: a change in circumstances. The authority to revisit an order comes from Family Code section 3651. (One exception: an order that is already below guideline can generally be moved up to guideline without showing a change in circumstances.)

Step 1. Something changed. A job loss, a raise, a new baby, a change in the parenting schedule. Income is the most common trigger, and most sources count, including unemployment, severance, and Social Security disability (SSDI), under Family Code section 4058. Need-based public assistance, such as SSI, is generally excluded. If you have just lost a job, the post on how a job loss affects support covers what shifts and what does not.

Step 2. See what the new number would be. Run your current incomes through the SupportSplit calculator for a quick estimate. To check that estimate against the court’s certified software at no cost, the Family Law Facilitator can run a guideline calculation for you (services vary by county), and several county law libraries offer XSpouse on their public research computers, including the Santa Clara County Law Library and the Alameda County Law Library.

Step 3. Ask for the new number. Either parent can ask the court to recalculate. There are three free ways to do this, covered in the next section, and the right one depends mostly on whether the other parent will agree.

Step 4. The hearing, then the new order. A judge reviews the updated numbers and issues a new order. The reason to file without waiting is timing: a modification can be made retroactive to the date the request was filed, not the date of the hearing, under Family Code section 3653. The existing order keeps running, and unpaid amounts become arrears, until the new order is signed.

Three free ways to get a modification

When circumstances have changed, there are three routes to a new order, and none of them require hiring anyone. Which one fits depends mostly on whether the other parent will agree to recalculate.

Option 1: Open a DCSS case. Either parent can open a case with the Department of Child Support Services at any time, whether or not an order already exists. The agency takes over the existing order and works from there, and it can establish, enforce, and review the amount, all for free. Because DCSS pursues the order through the court itself, the other parent refusing to cooperate does not stop it. Two things to know going in: DCSS represents the case, not you personally, and once it is involved the case runs through the agency, with payments and any wage withholding routed through the state, until it is closed. Case access is through Customer Connect.

Option 2: File a stipulation together, when the other parent agrees. If both parents agree to recalculate, they can visit the Family Law Facilitator together, have a guideline calculation run on the court’s certified software (XSpouse, which replaced DissoMaster in April 2025), and jointly file a Stipulation to Modify (FL-350) for a judge to sign. This is usually the lowest effort for everyone. One detail: if the agreed amount comes in below guideline, the court applies the conditions in Family Code section 4065 before approving it.

Option 3: File a Request for Order Either parent can file a Request for Order (FL-300) with an updated Income and Expense Declaration (FL-150). The other parent’s consent is not required. The Family Law Facilitator, a free office that every California superior court runs under Family Code section 10000 and following, will help you complete the forms at no cost, and filing sets a court date where a judge decides the number. It takes time, but a modification can be made retroactive to the filing date under Family Code section 3653, so filing sooner beats waiting for the right moment.

Run the certified software yourself, free at a law library. You do not have to take anyone’s word for the final number. XSpouse, the same program the courts now use, is available on the public research computers at several county law libraries at no charge. The Santa Clara County Law Library and the Alameda County Law Library both offer it, where you can generate a report and print it (around 25 cents a page) or save it to a USB drive. A web search for your own county law library plus “XSpouse” will show whether yours does the same. Note that law libraries provide the software but generally cannot give legal advice or one-on-one training.

What the court controls, and what it does not. Guideline support is the presumptively correct amount under Family Code section 4057, so neither parent can treat it as optional. The court does decide the inputs, though: if it finds a parent underemployed, it can impute income under Family Code section 4058(b), basing support on what they could earn rather than what they report. The California Courts self-help center is the full official guide.

Disclaimer

Knowing the above information does not replace advice about your specific situation, and it is not meant to replace an attorney. The purpose of this blog is to summarize existing documentation so you can walk into the Family Law Facilitator’s office, open a DCSS case, or use the free resources available to the public, all while understanding how things work and what the number is likely to be. The official links above are the source of truth. The calculator is there to give you the estimate first, so the rest of the process holds fewer surprises, and you save avoidable legal costs.

This post is for general information only and is not legal advice. For guidance on your own case, use the free Family Law Facilitator’s office in your county or consult a licensed California family law attorney.