Where to file and what you need before you start

In Illinois, you file for child support through your circuit court in the county where the child lives, or where the other parent lives. You do not file with the state or a federal office. The process starts with the Illinois Department of Child Support Services (DCSS) if you want them to collect payments on your behalf, or you can file directly with the court if you prefer to handle collection yourself.

Before you file, gather these documents: the child's birth certificate, proof of your income (pay stubs, tax returns, or a letter from your employer), proof of the other parent's income if you have it, and any existing court orders about custody or visitation. If you do not know the other parent's income, the court can order them to provide it during the case. You will also need the other parent's current address, or at minimum their full legal name and date of birth so the court can locate them.

The filing fee varies by county but typically ranges from $100 to $300. Some counties waive the fee if you cannot afford it; ask the circuit court clerk about a fee waiver when you arrive. If you are receiving TANF (Temporary Assistance for Needy Families) or SNAP benefits, you may be required to cooperate with child support enforcement as a condition of those benefits.

Key Takeaways

  • File at your county circuit court, not with the state, and bring your child's birth certificate, your income documents, and the other parent's address or identifying information.
  • You can file on your own or ask the Illinois Department of Child Support Services to handle collection, and the choice affects how payments reach you and what enforcement tools are available.
  • The court will calculate support based on both parents' incomes, custody time, and childcare costs using Illinois's income shares model, not a flat percentage.
  • If the other parent does not respond or does not show up, the court can enter a default order, but you still need to prove your income and the child's needs.
  • After an order is entered, you can modify it if either parent's income changes significantly or custody arrangements change.

Filing on your own versus using the state collection system

You have two paths. The first is to file a Petition for Child Support directly with the circuit court and handle collection yourself. The second is to ask the Illinois Department of Child Support Services to file on your behalf and collect payments through their system. Most people use DCSS because they handle enforcement and can garnish wages, intercept tax refunds, and suspend licenses if the other parent falls behind.

If you file on your own, you receive payments directly from the other parent, and you are responsible for following up if they do not pay. You can still ask the court to enforce the order later, but you have to initiate that action yourself. If you use DCSS, payments go to them first, they take a small fee (usually 2 to 4 percent), and then forward the money to you. DCSS also handles modifications and enforcement automatically if the other parent stops paying.

To use DCSS, contact your local child support office or apply through the Illinois DCSS website. They will file the petition for you at no cost. If you file on your own, you go directly to the circuit court clerk's office in your county with your petition and the filing fee.

The petition form and what information goes in it

The form is called a Petition for Child Support (or Petition for Modification of Child Support if an order already exists). You can get the blank form from your county circuit court clerk, from the Illinois Courts website, or from your local DCSS office. The form asks for your name and address, the other parent's name and address, the child's name and date of birth, and details about custody and visitation.

You must list your monthly income and the other parent's monthly income if you know it. Income includes wages, self-employment earnings, bonuses, rental income, and certain benefits. Do not guess at the other parent's income; if you do not know it, write "unknown" and the court will order them to provide it. You also list any childcare expenses, health insurance costs for the child, and any other children the other parent supports (because that reduces their support obligation to your child).

The form also asks whether custody is joint or sole, and how much time the child spends with each parent. Be accurate here because the court uses this to calculate the support amount. If custody is disputed, you may need to file a separate custody petition at the same time, or the court may address both in one hearing.

How the court calculates the support amount

Illinois uses the income shares model, which means the court adds both parents' incomes together, finds the combined amount in a state guideline table, and then divides that obligation between the parents based on their percentage of combined income. The court also factors in how much time the child spends with each parent, childcare costs, and health insurance premiums.

The calculation is not a simple percentage of one parent's income. For example, if you earn $40,000 per year and the other parent earns $60,000, the combined income is $100,000. The guideline table shows what the total support obligation should be for that income level (it varies by number of children). If you have one child, the table might say $1,200 per month. Since you earn 40 percent of the combined income, you would pay 40 percent of $1,200, or $480 per month. The other parent would pay 60 percent, or $720 per month. If you have custody most of the time, the other parent pays you their share; if custody is split, the higher earner typically pays the difference.

The court can deviate from the guideline if it finds that applying it would be unjust or inappropriate. This happens in cases where one parent has very high income, where there are multiple families involved, or where the custody arrangement is unusual. You can argue for a deviation, but you have to present evidence to the judge.

Serving the other parent and what happens at the hearing

After you file, the other parent must be served with a copy of the petition and a notice of the court date. Service means they receive official notice in a way the court recognizes. You cannot just hand them the papers yourself; the court clerk or a process server must deliver them. If the other parent's address is unknown, you can ask the court for permission to serve them by publication (posting a notice in a newspaper), but this takes longer.

The other parent has a set number of days to respond (usually 20 to 30 days). If they do not respond and do not show up at the hearing, the court can enter a default order based on what you presented. However, you still have to prove your income and the child's needs; the court will not award support without evidence. Bring your pay stubs, tax returns, and any documents showing childcare costs or health insurance expenses.

At the hearing, you and the other parent each present your income information and answer questions from the judge. If the other parent disputes your income or their own, the judge may order both of you to provide recent financial documents. The judge then applies the guideline calculation and enters an order. The order states the monthly support amount, when it is due, and how it should be paid (usually through wage garnishment or a payment service).

After the order is entered: payment and enforcement

Once the order is signed by the judge, it becomes legally binding. The other parent must pay the amount ordered by the due date each month. If they are employed, the court usually orders wage garnishment, which means the money comes directly out of their paycheck before they receive it. If they are self-employed or unemployed, they may pay through a payment service or directly to you.

If the other parent falls behind, you can ask the court to enforce the order. If you used DCSS, they handle enforcement automatically: they can intercept tax refunds, suspend a driver's license, report the debt to credit agencies, and in serious cases ask the court to hold the other parent in contempt. If you filed on your own, you have to file a motion to enforce and ask the judge to take action.

The order stays in effect until the child turns 18, or until they graduate from high school (whichever is later), unless the child is still in school after age 18. The order can also end if the child is adopted by someone else or if the child becomes emancipated.

Modifying the order if circumstances change

If either parent's income changes significantly, or if custody changes, either parent can ask the court to modify the support amount. A significant change is usually defined as a 10 percent or more change in income, or a substantial change in custody time. You do not have to wait for a specific time period; you can file for modification whenever the change occurs.

To modify, file a Petition to Modify Child Support with the same court that entered the original order. You will need to show proof of the income change (new pay stubs, a letter from your employer, or tax returns) or proof of the custody change (a new custody order or a written agreement). The process is similar to the original filing: the other parent is served, both sides present evidence, and the judge recalculates the support amount.

If you are using DCSS, you can ask them to file the modification for you. If you filed on your own, you file the modification petition directly with the court.

Frequently Asked Questions

What if I do not know where the other parent lives?

Tell the court clerk when you file. The court can order the other parent to provide their address, or DCSS can search for them using their Social Security number and other identifying information. If they cannot be located, you can ask the court for permission to serve them by publication, which means posting a notice in a newspaper. This delays the case but allows it to proceed.

Can I file for child support if we were never married?

Yes. Marital status does not matter. You file the same petition and follow the same process. If paternity is not established, the court may require a DNA test or a paternity acknowledgment before calculating support, but this is handled as part of the case.

What if the other parent is self-employed or has irregular income?

Bring tax returns from the past two years and any recent profit-and-loss statements. The court will average the income over time to find a reliable monthly figure. If income is very irregular, the judge may order the other parent to pay a base amount plus a percentage of income above a certain threshold, or may require quarterly adjustments.

How long does it take from filing to getting an order?

If the other parent responds and both sides agree on the amount, you can have an order within a few weeks. If the other parent does not respond, a default order can be entered within 30 to 60 days. If the case is contested, it may take several months, especially if the court needs to order financial disclosures or hold multiple hearings.

Can I get child support retroactively, back to when the child was born?

Illinois allows retroactive support, but only back to the date you filed the petition or the date you asked DCSS to open a case, not back to the child's birth. The court can order the other parent to pay arrears from that date forward if they have not been paying. If you want support from an earlier date, you need to file sooner rather than later.