One of the biggest misconceptions in Ontario family law: if you split parenting time equally, support payments disappear.
They don't. The higher-earning parent usually still pays child support—just calculated differently. And spousal support? That's a separate calculation entirely, though shared custody does affect it.
Here's how it actually works.
The Quick Answer
Child support with 50/50: The higher earner usually still pays, using the "set-off" method. Each parent's table amount is calculated, and the difference is paid.
The 40% threshold: Shared custody rules only kick in when each parent has the kids at least 40% of the time. Below that, it's calculated as sole custody.
Spousal support: Calculated separately, but shared custody can reduce the amount because the recipient has more ability to work.
First: Child Support vs. Spousal Support
These are two different things, and shared custody affects them differently.
Child support is money for raising the children. It's calculated using the Federal Child Support Guidelines and provincial tables. The amount is based primarily on the payor's income and number of children. Child support is the "child's right" and cannot be permanently contracted away by parents if the result is inadequate support. The CRA will not allow a payor to deduct spousal support unless all child support obligations are current. Any payment made is automatically applied to child support arrears first.
Spousal support is money from one spouse to the other to address the income gap between them. It's calculated using the Spousal Support Advisory Guidelines (SSAG) and is based on both incomes, length of marriage, and other factors.
Shared custody changes the child support calculation significantly. It affects spousal support less directly.
The 40% Rule: When Shared Custody Kicks In
Not every co-parenting arrangement counts as "shared custody" for support purposes. The threshold is 40% of parenting time for each parent.
| Parenting Time Split | Classification | Child Support Calculation |
|---|---|---|
| One parent has 60%+ | Sole custody | Standard table amount from non-custodial parent |
| Each parent has 40-60% | Shared custody | Set-off method (difference between table amounts) |
| Different children with different parents | Split custody | Each parent pays table amount for child(ren) with other parent |
What 40% Actually Means
40% of the year is approximately 146 days or nights. Courts typically count overnights, though daytime parenting can sometimes count too.
Common schedules that hit 40%+:
- Week on/week off: 50/50 — clearly shared custody
- 2-2-3 rotation: 50/50 — shared custody
- Every other weekend + one weeknight + half holidays: Often hits ~40%
Schedules that usually don't reach 40%:
- Every other weekend only: ~14% — sole custody calculation
- Every other weekend + one weeknight: ~25-30% — still sole custody
How Shared Custody Child Support Works
When both parents have 40%+ parenting time, child support uses the set-off method.
The Set-Off Calculation
Step 1: Calculate what each parent would pay the other based on their income and the child support tables.
Step 2: Take the difference. The higher earner pays that difference to the lower earner.
Example: Set-Off Calculation
Parent A income: $120,000/year
Parent B income: $60,000/year
Children: 2
Parenting time: 50/50
Step 1 — Table amounts:
Parent A would pay: $1,644/month (based on $120K income, 2 kids)
Parent B would pay: $892/month (based on $60K income, 2 kids)
Step 2 — Set-off:
$1,644 - $892 = $752/month
Result: Parent A pays Parent B $752/month in child support, even with 50/50 custody.
Why the Higher Earner Still Pays
The logic is straightforward: children should have a similar standard of living in both homes. If Parent A earns twice what Parent B earns, the children's experience at Parent B's home would be significantly worse without support flowing from A to B.
The set-off method reduces what the higher earner pays compared to sole custody—but doesn't eliminate it.
Section 9 Adjustments
The set-off amount is a starting point. Section 9 of the Child Support Guidelines allows courts to consider additional factors:
- The actual costs each parent incurs for the children
- The condition, means, and needs of each parent and child
- Any special or extraordinary expenses
In practice, courts often use the set-off amount as-is. But if one parent can show they bear significantly more child-related costs (larger home for the kids, more activities expenses, etc.), adjustments are possible.
How Shared Custody Affects Spousal Support
Spousal support is calculated separately from child support—but shared custody does influence it.
The SSAG With-Child Formula
When there are dependent children, the SSAG uses the "with-child" formula. This formula factors in:
- Both spouses' incomes
- Child support being paid
- The number and ages of children
- Who has primary care of the children
With shared custody, the child support amount is lower (because of the set-off), which affects the spousal support calculation. And the custodial arrangements themselves matter.
Why Shared Custody Can Reduce Spousal Support
1. Less childcare burden on the recipient
One factor in spousal support is the recipient's ability to work. If you're the sole caregiver for young children, your work options are limited. But with 50/50 custody, you have significant child-free time to work, retrain, or build your career. Courts recognize this.
2. The set-off child support is already income-sharing
Child support payments transfer money from higher earner to lower earner. The SSAG accounts for this—it doesn't want to "double count" the income sharing that's already happening through child support.
3. Both parents have similar child-related costs
With sole custody, the custodial parent bears most child-raising costs. With shared custody, costs are more evenly distributed. This can affect the recipient's demonstrated "need" for support.
Example: Spousal Support Difference
Scenario: 12-year marriage, 2 children, incomes $150K and $50K
With sole custody (kids with lower earner):
Child support: ~$1,968/month
Spousal support range: ~$1,200-$1,800/month
With shared custody (50/50):
Child support: ~$1,100/month (set-off)
Spousal support range: ~$800-$1,400/month
Note: These are rough estimates for illustration. Actual amounts depend on many factors.
Common Misconceptions
Misconception 1: "50/50 means no support"
Reality: The higher earner almost always pays something. Equal parenting time doesn't erase the income gap. Both child support (set-off amount) and spousal support (if there's an income difference and sufficient marriage length) typically still apply.
Misconception 2: "I want 50/50 to avoid paying support"
Reality: Courts can see through this. If your motivation for seeking shared custody is financial rather than about the children's best interests, it won't go well. And even if you get 50/50, you'll likely still pay support—just less.
Misconception 3: "We can agree to no support with 50/50"
Reality: You can agree to it, but there are risks. Child support is the child's right, not the parents'. Courts can override agreements that leave children inadequately supported. And if circumstances change, the lower-earning parent could later claim arrears for support that should have been paid.
Misconception 4: "39% is basically 40%"
Reality: Nope. The 40% threshold is a bright line. Courts have consistently held that parenting time just under 40% doesn't qualify for shared custody treatment. If you're at 39%, you're in sole custody territory for support calculations.
Misconception 5: "Daytime hours count the same as overnights"
Reality: Courts typically count overnights as the primary measure. Daytime parenting can sometimes factor in, but overnights are the standard metric. A schedule with lots of after-school time but few overnights may not hit 40%.
Split Custody: A Different Situation
Split custody is different from shared custody—and people confuse them constantly.
Shared custody: Both parents share time with all children (each has 40%+ time with the same kids).
Split custody: Each parent has primary custody of different children. Example: Daughter lives mostly with Mom, Son lives mostly with Dad.
How Split Custody Support Works
With split custody, each parent pays child support for the child(ren) living primarily with the other parent. Then you take the difference.
Example: Split Custody
Parent A income: $100,000 (Daughter lives primarily here)
Parent B income: $70,000 (Son lives primarily here)
Parent A pays for Son: $855/month (1 child, $100K income)
Parent B pays for Daughter: $636/month (1 child, $70K income)
Net: Parent A pays Parent B $219/month ($855 - $636)
Special Expenses: Section 7
On top of basic child support, parents share "special or extraordinary expenses" (Section 7 expenses). These include:
- Childcare costs
- Health-related expenses not covered by insurance
- Educational expenses (tutoring, private school)
- Post-secondary education costs
- Extracurricular activities
Section 7 expenses are typically shared in proportion to income. If Parent A earns 65% of combined income and Parent B earns 35%, they split Section 7 costs 65/35.
This applies regardless of custody arrangement. Whether you have sole, shared, or split custody, Section 7 expenses are split based on income.
What If Parenting Time Changes?
Parenting arrangements often evolve. Kids get older, work schedules change, someone moves. What happens to support?
Crossing the 40% Threshold
If parenting time changes enough to cross the 40% threshold in either direction, child support should be recalculated:
- Going from 35% to 45%: You now qualify for shared custody set-off calculation. Child support should decrease.
- Going from 45% to 35%: You no longer qualify for shared custody. Child support should increase (standard table amount applies).
Support doesn't change automatically—you need to either agree on new amounts or go to court for a variation.
Document Your Parenting Time
If you're close to the 40% threshold, keep records of actual parenting time. Calendars, texts confirming pickups/dropoffs, anything that shows the real schedule. If there's ever a dispute about whether you hit 40%, documentation matters.
Negotiating Shared Custody Support
If you're negotiating a separation agreement with shared custody, here are the key points:
Be Specific About the Schedule
Spell out the parenting schedule in detail. "Approximately 50/50" invites disputes. A specific rotation (week on/week off, 2-2-3, whatever works) creates clarity.
Address Schedule Changes
What happens if the schedule changes? Build in a mechanism for adjusting support if parenting time shifts significantly.
Don't Forget Section 7
Agreeing on base child support is only part of it. Specify how you'll handle Section 7 expenses—which ones qualify, how they're approved, how they're split.
Consider the Tax Implications
Child support isn't taxable or deductible. Spousal support is. If you're trading off between the two, understand the tax impact. A dollar of spousal support is worth less to the recipient (taxable) but costs less to the payor (deductible) than a dollar of child support.
Try the Calculators
Want to see how support might work in your shared custody situation?
Our child support calculator handles shared custody calculations. Enter both incomes and select the shared custody option to see the set-off amount. Then use the spousal support calculator to see how that affects the overall picture.
Frequently Asked Questions
Do I still pay child support with 50/50 custody?
Usually yes. With shared custody (40%+ parenting time each), the higher-earning parent typically still pays child support—just less than they would with sole custody. The calculation uses the "set-off" method: each parent's table amount is calculated, then the difference is paid by the higher earner.
What counts as shared custody for child support in Ontario?
Shared custody applies when each parent has the children at least 40% of the time (about 146 nights per year). Below 40%, it's considered sole custody for support purposes, even if you have significant parenting time. The 40% threshold is strict—39% doesn't count as shared custody.
How does shared custody affect spousal support?
Shared custody can reduce spousal support because: (1) the recipient has less childcare burden limiting their work availability, and (2) the set-off child support calculation already accounts for some income sharing. However, spousal support is still calculated separately based on income differences and marriage length.
What is the set-off method for child support?
The set-off method calculates what each parent would pay the other based on their income and the child support tables, then takes the difference. Example: Parent A would pay $800, Parent B would pay $400. The set-off amount is $400, paid by Parent A to Parent B.
Is split custody the same as shared custody?
No. Split custody means each parent has primary custody of different children (e.g., one child lives mostly with mom, another mostly with dad). Shared custody means both parents share time with all children (each has 40%+ time). The calculations are different.
Can we agree to no child support with 50/50 custody?
You can agree to it, but courts may not enforce an agreement that leaves children under-supported. Child support is the child's right, not the parents'. If there's a significant income difference, a court might override your agreement. Also, if circumstances change, the lower earner could later claim the support that should have been paid.
Related Articles
- Why Is My SSAG Range So Wide? — Understanding spousal support calculations
- Property Division vs Spousal Support — Two separate calculations
- Tax Rules for Spousal Support — CRA implications
- Imputed Income — When income is calculated differently