Spousal support calculator · Ontario · 2026
Spousal support, in the range Ontario actually uses.
Ontario follows the Spousal Support Advisory Guidelines, which produce a range — low, middle, and high — plus how long support lasts. Cairn runs the formula that matches the inputs you give it and shows you all of it.
Both formulas
With-children (after-tax income) and without-children (gross income plus years) — Cairn applies the one that matches whether you entered dependent children.
Range, not a single number
Low, middle, and high amounts plus how long support lasts. Honest about what the Guidelines actually produce.
Two paycheque scenarios
What hits your account before and after a paycheque adjustment — so you can see what filing the T1213 actually changes for your monthly cash flow.
Cairn's Ontario spousal support calculator is a free tool that estimates support under the Spousal Support Advisory Guidelines — no account, no fee. Spousal support in Ontario follows the Spousal Support Advisory Guidelines — the framework family lawyers and judges work from. The Guidelines are not law in the strict sense; they are advisory. But they are the working framework, and most negotiated settlements land somewhere inside the range they produce.
There are two formulas, and which one applies depends on whether dependent children are part of the picture. Without dependent children, the math runs off the difference in gross incomes and how long the relationship lasted. With dependent children, the math runs off each party's after-tax income (with child support already taken into account) and is more sensitive to who has primary care of the kids.
Cairn applies the with-children or without-children formula depending on whether you entered dependent children, and produces the low, middle, and high amount and the duration range. When the receiving spouse's age plus the years of the relationship adds up to 65 or more — and the relationship was at least five years — support runs open-ended rather than for a set period.
One thing to understand: this calculator estimates the quantum range and duration that would apply if spousal support is owed. Whether it is owed at all — entitlement — is a separate threshold legal question that turns on the circumstances of your relationship, and Cairn does not assess it. Confirm entitlement by getting legal advice before you rely on these numbers.
The calculator also runs the full Ontario tax math — federal and Ontario tax, Canada Pension Plan contributions, Employment Insurance — and shows your take-home per pay period. If you are the paying spouse, it adds a second view: what your paycheque would look like if Canada Revenue Agency agreed to reduce the tax taken off each pay to reflect the support deduction (the form for that is T1213, covered on its own page).
Your income, and your spouse's
Both of your gross annual incomes — what you each make in a year before tax.
What you make in a year before tax. Use last year's tax return if it's handy, or your most recent T4.
The same number for your spouse — what they make in a year before tax. Your best honest estimate is fine.
Your kids and how time is shared
How many, their ages, and where they live most of the time.
Children of the relationship who still depend on the two of you. Enter 0 if there are none.
Time together, and ages
How long you've been a couple, plus both your ages.
Count the years you've been a couple, even before marriage. If you lived together for two years before getting married six years ago, enter 8.
We need this to figure out the realistic range for how long support might be paid.
Same reason — age and length of relationship together affect how long support typically lasts.
Methodology reviewed May 6, 2026 · Cross-validated against DivorceMate Tools One · See full sources · How spousal support works · Read the guide
Common questions
The questions men ask about Ontario support.
Plain-language answers about how the Federal Child Support Guidelines and the Spousal Support Advisory Guidelines actually work in Ontario.
About Cairn
Cairn is an Ontario-built preparation tool for men going through separation. It gives you orientation, document checklists, and the financial picture in plain language — so you can prepare and then work with a legal professional.
Keep your numbers
Save this to a free Cairn account.
- Keep these numbers alongside your full separation plan
- Your specific Ontario next steps, in order
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