Unpaid child support in California is not a tab you work out later. Each missed installment is already an enforceable judgment installment, and interest starts the day it was due. The demand packet puts principal, interest, and a payment channel in one place — and it splits what you send the Department of Child Support Services from what you send the parent who was ordered to pay. Below is a filled, clearly hypothetical arrears sketch, plus the paragraphs that travel with it.
What California Law Says
A child support order is enforceable until it is paid in full. Family Code section 291 says a support judgment does not expire for lack of renewal. Family Code section 290 lets the court enforce it by execution, receivership, contempt, or any other order the court finds necessary.
Interest is not "Family Code 685.010." That section does not exist. The rate is in Code of Civil Procedure section 685.010: 10 percent per year on the principal amount of a money judgment remaining unsatisfied. The 5 percent rate that same section added for certain personal-debt and medical-expense judgments does not describe child support. Code of Civil Procedure section 695.211 requires every child support judgment or order to notice that interest on arrearages accrues at the legal rate, and it requires a local child support agency statement of account to show current support, arrears, and interest. The DCSS arrears calculator cites section 685.010 and the 10 percent figure, with narrow exceptions (a different rate in the order, another state's legal rate, or a qualifying active-duty reduction). DCSS treats it as simple interest on unpaid principal.
Interest runs on each unpaid installment from that installment's due date. A January 1 payment does not wait until December to start accruing.
A court order does not automatically open a DCSS case. DCSS's FAQ states that a private (non-IV-D) case stays private until a parent asks the local child support agency for help. You have the right to open that case. If you do not receive public cash assistance and collections later run through DCSS, the agency currently discloses a $35 annual fee on cases that receive at least $550 in a year.
A demand letter does not replace income withholding, a DCSS case, or contempt. It documents the running balance and gives the agency a clean packet.
How to Build and Send the Arrears Demand Packet, Step by Step
Jordan Hale is not a real person. The case number is fake. Use your order and today's date.
The hypothetical. Los Angeles County Superior Court Case No. 22STFL99999 (hypothetical). Jordan Hale is the custodial parent. Alex Hale was ordered on March 4, 2024 to pay $875 per month, due the 1st, plus health insurance when available. Nothing posted from January 1 through August 1, 2026. Computation date: August 28, 2026. September support is not yet due, so it stays out of the table.
- Pull the filed order, every modification, every wage-withholding order, and a month-by-month payment record. If DCSS already has the case, print the Customer Connect statement or call 1-866-901-3212 and write down principal, interest, and the participant ID.
- Build a month-by-month sketch, not a lump. A practical simple-interest formula for one missed month is: installment × 0.10 × (days late ÷ 365).
| Due date | Ordered | Paid | Principal unpaid | Days late as of 8/28/2026 | Interest (10% simple) |
|---|---|---|---|---|---|
| 1/1/2026 | $875.00 | $0 | $875.00 | 239 | $57.29 |
| 2/1/2026 | $875.00 | $0 | $875.00 | 208 | $49.86 |
| 3/1/2026 | $875.00 | $0 | $875.00 | 180 | $43.15 |
| 4/1/2026 | $875.00 | $0 | $875.00 | 149 | $35.72 |
| 5/1/2026 | $875.00 | $0 | $875.00 | 119 | $28.53 |
| 6/1/2026 | $875.00 | $0 | $875.00 | 88 | $21.10 |
| 7/1/2026 | $875.00 | $0 | $875.00 | 58 | $13.90 |
| 8/1/2026 | $875.00 | $0 | $875.00 | 27 | $6.47 |
| Totals | $7,000.00 | $0 | $7,000.00 | $256.02 |
Principal $7,000.00 + interest $256.02 = $7,256.02 as of August 28, 2026. Interest keeps running on unpaid principal. Recalculate after every posting. If DCSS already maintains the official balance, use the agency's numbers in the letter and attach the statement. Your spreadsheet is then a check, not a competing ledger.
- Write the payor demand in numbered facts. Sample paragraphs:
Re: Child support arrears — Hale v. Hale, Los Angeles County Superior Court Case No. 22STFL99999 (use your real number)
You were ordered on March 4, 2024 to pay $875.00 per month in child support, due the first of each month. No payment has been received for the installments due January 1, 2026 through August 1, 2026. Principal arrears are $7,000.00.
Under Code of Civil Procedure section 685.010, interest accrues at 10 percent per year on unpaid principal. Computed as simple interest on each missed installment through August 28, 2026, accrued interest is $256.02. The total now due is $7,256.02, plus additional interest until principal is paid, plus the $875.00 current support due September 1, 2026.
Demand is made that you pay $7,256.02 immediately and resume current support on time. Pay through the State Disbursement Unit or the income withholding order already in place — not a new personal side channel.
If this remains unpaid I will deliver this packet to the local child support agency and seek the enforcement tools the order already supports. This is a demand for amounts already ordered. It is not a modification.
Attach the order, the table, and proof of nonpayment. Send the payor copy certified mail, return receipt requested, and keep the green card.
- Send DCSS a different cover. The agency does not need a threat paragraph. It needs a case-opening or case-update file: the application for services if this is still private (start at childsupport.ca.gov); a filed copy of the order and every modification; your table labeled "unofficial reconstruction as of August 28, 2026 — please reconcile to the agency ledger"; the payor's last known address, employer, and Social Security number if you have them; and a copy of the demand plus the certified-mail receipt.
Do not argue custody in the DCSS cover. The agency does not handle custody or visitation. Do not tell the payor to pay you in cash "to make us even" if withholding already routes money through the SDU. That is how credits get lost.
- Log two follow-ups. Ten days: did the green card come back? Fourteen days: if this is a new DCSS case, get the participant ID and enroll in Customer Connect. Recalculate on the 1st of each month until principal is gone.
Common Questions
Is the interest really 10 percent, and is it Family Code 685.010?
It is 10 percent per year on unpaid principal under Code of Civil Procedure section 685.010, which is the statute DCSS cites on its arrears calculator. Family Code section 685.010 does not exist. Section 695.211 is the child-support notice rule: the order must tell the parties that interest on arrearages accrues at the legal rate. Do not apply the 5 percent personal-debt rate to support. If the local agency already shows a balance, use that balance.
If DCSS is already on the case, do I still send a demand to the other parent?
You can. It does not replace the agency. Send DCSS the updated table and a copy of whatever you mailed. Send the payor a factual demand that points payments to the SDU or the existing withholding order. The agency case is how you reach intercepts and the official ledger. The demand letter is how you prove the payor was told the number while interest was running.
Get the free Child Support Collection Kit at justiceprompt.com — arrears worksheets, demand-letter templates, and the DCSS versus payor checklist. Free, no email wall. The same collection resources live at childsupportcollection.org. Educational use only — not legal advice.
California Child Support Recovery System 
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