How spousal support works in Ontario — entitlement first, then the range, then how long it lasts.

Ontario recognises three grounds for spousal support. Compensatory: one spouse gave up earning power or career progress for the relationship or to raise the children, and the other benefited. Needs-based: one spouse cannot meet reasonable expenses after separation while the other can. Contractual: you agreed, in a marriage contract or separation agreement, that support would be paid.

If none of those applies — two similar incomes, a short relationship, no one stepped back from work — there may be no entitlement, and no support is owed no matter what a formula would generate. This is the single most misunderstood part of spousal support. The formula does not create the obligation. The entitlement does. The formula only sizes it once entitlement is established.

The without-children formula applies when there are no dependent children. Support runs at roughly 1.5 to 2 percent of the gross income difference between you for each year you lived together, to a ceiling of 50 percent of that gap. A fifteen-year marriage with a large income difference produces a wide, substantial range; a four-year marriage with a small gap produces a narrow, modest one.

The with-children formula applies when child support is also being paid. It does not work from gross income. It works from each spouse's net income after child support and tax, and targets a share of the combined net income so both households land in a reasonable range. It is genuinely complex — this is the formula where doing it by hand goes wrong, and where a calculator earns its place.

Both formulas give a low, mid, and high figure. Where you land in that range depends on the specifics: the length of the relationship, the size of the gap, the ages, and how the rest of the settlement is structured.

For relationships without dependent children, the SSAG set a duration range of roughly half a year to one year of support for every year you were together. A ten-year marriage points to somewhere between five and ten years of support, with the exact length negotiated inside that band.

The Rule of 65 is the exception that matters. When the years you lived together plus your age at separation add up to 65 or more, support can be indefinite — meaning it has no fixed end date. Indefinite does not mean forever and does not mean unchangeable; it means there is no automatic stop, and either side can ask for a review when circumstances change.

Where there are dependent children, duration is tied to the parenting arrangement and the children's needs rather than a fixed multiplier, and is usually reviewed as the children grow.

Spousal support is one area where common-law partners are treated almost the same as married spouses. In Ontario, a common-law partner can claim support after living together for three years, or after living together in a relationship of some permanence with a child. The same SSAG formulas, the same entitlement test, the same duration rules.

Property is the opposite story. Common-law partners do not get the equalization of net family property that married spouses get — the even split of what each gained during the marriage. That difference is large enough to have its own guide.