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How to Modify Child Support in California

California law lets parents adjust child-support orders when life changes. This guide walks you through eligibility, paperwork, timelines, and courtroom tips—everything you need to file a solid request in under 10 minutes of reading.

Parent completing FL-300 request for order to change child support

$60–85

Typical filing fee (ask for a fee-waiver if you qualify)

30–90 Days

Average processing time from filing to new order

10 %+

Common income change threshold courts recognize

Five Clear Steps to Modify Child Support in California

1. Confirm You Have a “Material Change”

Before you fill out a single form, make sure your situation meets California’s material change in circumstances requirement (Family Code § 3651). Courts look for something substantial—usually a shift that would change guideline support by at least 20 %. Classic examples include a job loss, income spike, new health-insurance premiums, or a custody schedule moving from 70/30 to 50/50. If you recently switched to equal parenting time and wonder “can you lower child support after custody change California?”—this is exactly the test judges use.

2. Gather Persuasive Evidence

Paper beats promises. Collect recent pay stubs, the last two years’ federal and state tax returns, unemployment-benefit award letters, child-care receipts, health-insurance statements, and an updated parenting calendar. Each document backs up the numbers you’ll place in Form FL-150. Judges often deny requests that lack hard proof or rely on “my paycheck is smaller” assertions without exhibits.

3. Complete the California Child Support Modification Forms

This is the heart of the process. You will file Form FL-300 (Request for Order) and Form FL-150 (Income & Expense Declaration). Optional Form FL-335 helps you prove service. Below is a mini checklist of what to enter—your “FL-300 instructions step by step” condensed:

  • Caption boxes: Case number, court address, parties’ names—copy exactly from your last order.
  • Item 3a: Check “Modify Child Support” and describe the change (e.g., “Income decreased by 25 %”).
  • Item 10: Attach a proposed guideline calculation—use our Child Support Estimator and print the summary.
  • FL-150: Make sure it’s signed within 90 days of the hearing date; attach pay stubs.

For a deeper dive on “California child support modification forms,” see our forthcoming detailed FL-300 guide.

4. File & Serve the Packet

Take two copies plus the originals to the clerk or e-file system. Fee waivers (FW-001 & FW-003) wipe out the $60–85 filing cost if you qualify. After the clerk stamps hearing dates, personally serve the other parent at least 16 court days before the hearing (add 5 calendar days if by mail). A non-party adult or professional process server can handle delivery.

5. Prepare for the Hearing

Bring the original + two copies, your proof of service, and any fresh financial documents. Judges appreciate concise statements: outline the change, reference Family Code § 4055 guideline print-out, and highlight exhibits. If your income is variable, be ready to explain monthly averages or why the court should not impute income. Updated FL-150s less than 90 days old carry extra credibility.

Real-Life Triggers for Child Support Modification

Job Loss

Sam was laid off from his sales job and unemployment now pays 45 % of his old salary. He attached EDD award letters and last three pay stubs to prove income drop— classic “job loss child support change California” scenario.

Income Increase

Mia’s promotion raised her base salary by 30 %. Her ex submitted new pay stubs and offer letter showing the raise—evidence that can justify a support hike.

Medical Costs

Chloe’s child developed asthma requiring $450/month in prescriptions. Receipts and insurance EOBs supported a guideline deviation for unreimbursed medical add-ons.

Custody Shift

After moving closer to school, Jordan increased overnight time from 20 % to 50 %. He filed the new parenting plan to show the altered percentage timeshare.

Common Grounds & Proof You’ll Need

Ground for Modification Key Proof to Attach
Job Loss / Reduced Hours EDD benefit letter, termination notice, last pay stub showing hour cut
Income Increase New pay stubs, offer letter, commission statements
High Medical Expenses Invoices, pharmacy receipts, insurance Explanation of Benefits (EOB)
Custody Schedule Change New parenting plan (FL-341 or stipulation) and attendance records
Incarceration of Payor Commitment order, jail booking sheet, income verification from facility

How to File Without a Lawyer

A surprising number of Californians succeed as self-represented litigants—often called “pro pers.” The key is preparation: know the forms, follow local rules, and arrive early on hearing day. Court self-help centers can review paperwork for free, and many counties offer a family-law facilitator who will check guideline calculations. Ready to dive deeper? Our full DIY guide walks step-by-step through e-filing portals, courthouse windows, and service options.

Quick Document Checklist

  • ✔️ Recent tax returns (2 years)
  • ✔️ Last 3 months’ pay stubs or unemployment statements
  • ✔️ Child-care cost receipts
  • ✔️ Health-insurance premium statement
  • ✔️ Current parenting calendar
  • ✔️ Completed FL-300 & FL-150

Frequently Asked Questions

There is no waiting period in California—as long as you can show a material change, you may file immediately. Practically, judges expect at least a few months between orders unless an emergency arises.

You can file Form FL-300 requesting the court to compel disclosures. Judges may impute income, issue sanctions, or postpone the hearing until the non-cooperative parent produces documents. Bring a written request and proof you asked for the information.

California allows retroactive adjustments only back to the date you served the request for order. Any arrears that accumulated before service usually remain unless both parents agree in writing or the court finds good cause, which is rare.

Yes. The court requires an updated Income & Expense Declaration from both parents, even if only custody time has shifted. Leaving FL-150 blank or attaching an old version invites continuances or outright denial.

Self-employment income requires profit-and-loss statements, bank records, and tax returns. Courts may average income over 12–36 months or impute a reasonable wage based on industry standards. Provide detailed ledgers to avoid inflated imputation.

Related Guides

Material Change – A substantial shift that justifies revisiting support.
Arrears – Past-due support still owed after the due date.
Wage Assignment – Court order directing an employer to deduct support.
Imputed Income – Earnings the court assigns when actual income is unclear.
Read more in our full glossary.