The Federal Child Support Guidelines, Section 7 expenses, gross income rules, and the common mistakes that leave people paying or receiving the wrong amount.
Child support in Canada is not a negotiation in the traditional sense. The Federal Child Support Guidelines set the base amount by law, and neither parent can agree their way out of it. Understanding how the system works, and where the common mistakes happen, puts you in a much better position going in.
The starting point for every child support calculation is the Schedule I tables in the Federal Child Support Guidelines. The tables are province-specific because provincial tax rates differ, which affects after-tax income and therefore what's fair.
The three inputs are:
The output is a monthly dollar amount. There's no formula to run, you look up the income in the table and read the number.
To give you a sense of the scale (Ontario, 2024 tables):
| Gross income | 1 child | 2 children |
|---|---|---|
| $60,000 | $557/month | $831/month |
| $80,000 | $743/month | $1,103/month |
| $100,000 | $933/month | $1,383/month |
| $120,000 | $1,121/month | $1,679/month |
These are base amounts. They're the floor, not the ceiling.
This is the single most common mistake: using net income instead of gross.
The Guidelines use gross income, your total income before tax. Not what you deposit in your bank account each month. Section 16 of the Guidelines defines income broadly: employment income, self-employment income, rental income, dividends, interest, and more.
The most reliable source is Line 15000 of your CRA Notice of Assessment (total income), with Schedule III adjustments applied. Schedule III allows certain deductions, union dues, for example, but does not allow RRSP contributions to reduce child support income.
If you've been calculating based on your net income, your number is likely significantly low.
Section 7 of the Guidelines covers "special or extraordinary expenses." These are added to the table amount and shared proportionally between both parents based on their incomes. They are not discretionary, if an expense qualifies, it gets shared.
Section 7 expenses include:
The proportional split works like this: if Parent A earns $80,000 and Parent B earns $40,000, combined income is $120,000. Parent A holds 67% of combined income and pays 67% of shared Section 7 costs; Parent B pays 33%. That's separate from, and on top of, the table amount.
Section 7 is where a lot of separation agreements fall short. The table amount gets set and Section 7 is handled vaguely or not at all. That creates ongoing disputes about who pays for braces, summer camp, or university tuition. Be specific from the start.
When a child spends at least 40% of their time with each parent, the standard table calculation doesn't automatically apply. Section 9 of the Guidelines allows the court to look at:
The 40% threshold works out to roughly 146 nights per year, or about 6 nights in every two-week period. Courts count all time with the child, not only overnights, though overnights are the most commonly used measure.
What Section 9 does not mean: child support disappears at 40% time-sharing. Courts still look at the real economic impact on both households. The higher-earning parent typically still pays something to the lower-earning parent, often a reduced amount calculated by offsetting the two table amounts and adjusting for the actual parenting costs each parent carries.
Courts can, and do, impute income to a paying parent who appears to be earning less than they could be. This applies when a parent is intentionally unemployed or underemployed without a reasonable explanation.
Common situations where courts impute income:
When income is imputed, child support is calculated on what the court determines the parent could earn, not what they're currently reporting.
Child support amounts should be updated whenever income changes materially. Under Section 25 of the Guidelines, both parents are required to disclose their income annually. If the paying parent's income goes up and support isn't adjusted, the difference can be claimed retroactively.
The Supreme Court of Canada confirmed in DBS v SRG (2006) that courts can order retroactive child support going back up to three years. Failing to proactively disclose income increases and adjust support accordingly is an exposure most paying parents don't think about until it's a problem.
Quebec operates under its own child support model, the Regulation respecting the determination of child support payments, rather than the Federal Guidelines. The Quebec model considers both parents' incomes, the custody arrangement, and produces different amounts than the federal tables. If you're in Quebec, use the provincial model, not the federal tables.
Parents cannot agree between themselves to pay less than the Federal Guidelines table amount without court approval. Courts won't approve below-table support without a compelling reason. An agreement to pay below-table is not enforceable, the receiving parent can return to court and get the table amount regardless of what was agreed.
You can agree to pay more than the table amount. You cannot meaningfully agree to pay less.
FairWell's child support calculator uses the actual Federal Child Support Guidelines tables and walks through Section 7 expenses so you can arrive at an accurate, defensible number before sitting down to negotiate. Knowing your number matters, it's much harder to unknowingly agree to the wrong amount if you know what the right one is.
This guide is for informational purposes only. FairWell is not a law firm and this is not legal advice. Every situation is different, consult a qualified family lawyer in your province or state.
FairWell's child support calculator uses the real Federal Guidelines tables, walks through Section 7, and handles shared custody scenarios.
Use the calculator →Before finalising any child support arrangement, speak with a qualified family lawyer in your province.