My spouse and I each own a separate company — does CRA consider them associated for tax purposes?

Potentially, yes. The associated corporation rules include specific provisions dealing with related persons, and spouses are treated as related for these purposes, so two corporations owned separately by spouses can still be found associated depending on how control and ownership actually work between them, simply having each spouse hold their own company separately doesn't automatically avoid association if the underlying relationship and control patterns meet the statutory tests.

Whether association actually applies turns on the specific facts: things like whether the spouses' combined interests amount to control of both corporations under the relevant deeming rules, and whether there are other connections between the businesses, such as shared operations, common customers, or cross-involvement in each other's company. It isn't automatic just because two people are married and each owns a company, but the possibility is real enough that it shouldn't be assumed away.

Because the rules here are genuinely technical and the consequence, sharing a single small business limit instead of each corporation getting its own, matters significantly to a couple's overall tax bill, spouses running separate corporations should have their specific structure reviewed against the associated corporation rules rather than assuming separate ownership by itself settles the question.