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Separation and Divorce: Child Support

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How do parents decide on the amount of child support?

If parents agree

Some parents discuss and agree on the amount of child support on their own.

If they do, they can put what they agree on in a written agreement called a separation agreement. An agreement can deal with child support alone, or can also include other issues like spousal support, decision-making responsibility or custody, parenting time or access, and dividing property.

Parents do not need a lawyer to make an agreement. But it is a good idea for each parent to get their own legal advice before signing one. Parents cannot get advice from the same lawyer.

Usually, the parents agree on child support based on the Child Support Guidelines.

In some cases, parents agree not to follow the Guidelines. But they should look at the Guidelines before deciding on the amount of support to make sure it is reasonable. If they do not follow the Guidelines, their agreement should say why not.

If a parent later asks the court to order child support that is different from their agreement, the court looks at what it would have ordered under the Guidelines.

If parents don't agree

If parents cannot agree on the amount of child support to be paid, they can:

  • get help from a family law professional
  • use the Ontario government's online Child Support Service
  • go to family court

Get help from a family law professional

Family law professionals are people who work with both parents to help them reach an agreement. Some family law professionals are neutral, which means they do not take sides. In some cases, they can also make a decision when parents don't agree.

Family law professionals can work in:

  • mediation
  • arbitration
  • mediation-arbitration
  • collaborative family law
  • parenting coordination

These processes are sometimes called family dispute resolution or alternative dispute resolution (ADR) processes because they try to solve issues without going to court. Parents must think about using ADR to resolve their issues, but only if it's suitable for their situation.

ADR is voluntary. So a parent cannot be forced to agree to use ADR.


The Ministry of the Attorney General offers free and sliding-scale mediation services in family courthouses. Sliding-scale means the amount a parent pays depends on their income and the number of children they have to support.

To find out more about these services, search for "Family Mediation Services" on the Ministry's website at

Parents can also hire a private mediator.

Use the Ontario government online service

Some parents can apply to use the Ontario government's online Child Support Service (CSS) to calculate child support.

Usually, CSS can only decide child support in simple cases where the table amount applies. It can only be used for some special or extraordinary expenses. And, it cannot calculate retroactive child support.

The CSS uses income information from the parents to calculate how much child support should be paid. This is usually based on a parent's tax return. Based on this income information, the CSS then mails the parents a Notice of Calculation that tells them how much child support must be paid. Parents are expected to follow this Notice like a court order.

The CSS can be used to set up child support only if all of these things are true:

  • both parents agree to use CSS
  • the payor parent gives income information
  • each parent pays a fee, but if their income is low enough, a parent can apply to have the fee waived
  • CSS applies to their situation.

CSS will not apply if any of the following are true:

  • one parent does not live in Ontario
  • any of their children are older than 17.5 years, or are married
  • the payor parent gets more than 20% of their income from self-employment, rental income, or investment income
  • the parents have shared or split parenting time

Visit and click the "Set up or update child support" button to access the CSS.

Go to court

If parents cannot agree on child support or to use the CSS, either parent can start a court case and ask a judge to decide.

Going to court can be a complicated process and take a lot of time. It can be stressful and expensive, but it is sometimes necessary to decide the issues.

Judges decide child support by using the Child Support Guidelines. The only times the court can order amounts without applying the Guidelines are when:

  • both parents agree and the judge thinks the plans made for child support are reasonable, or
  • the judge thinks that the Guideline amount would be unfair because there is some special arrangement that benefits the child.

Even after the court process has started, parents can stop it by making an agreement. Many steps in the court process encourage parents to agree.

The flowcharts in CLEO's Steps in a Family Law Case can help parents understand and follow the court process. Visit