If you already own a corporation and you buy another, the two may be “associated” from the moment control changes hands. Associated Canadian-controlled private corporations do not each get a $500,000 small business limit. They share one — permanently, under a test in section 256 of the Income Tax Act that asks who controls what, not whether the businesses have anything to do with each other.
Key takeaways
SECTION 01 OF 08
Income Tax Act s. 256(1), marginal note Associated corporations, associates two corporations if, “at any time in the year”, one of five paragraphs applies. Paragraph (b) is the one most buyers meet: “both of the corporations were controlled, directly or indirectly in any manner whatever, by the same person or group of persons”.
You own Company A. You buy the shares of Company B. From closing, the same person controls both. That is the whole test. It does not ask whether A and B trade with each other at all.
Treadstone Law agrees in its overview of associated corporations: the rules “generally turn on control and common ownership rather than on whether the businesses actually operate together day to day.” CRA goes further in its guidance on how relationships affect the deduction: a “group of persons” can be formed by “any two or more persons and the members of the group do not have to act together or have any connection to each other.”
SECTION 02 OF 08
Paragraphs (c) to (e) reach further. Paragraph (c) applies where each corporation is controlled by a person, the two are related, and “either of those persons owned, in respect of each corporation, not less than 25% of the issued shares of any class, other than a specified class”.
Related is defined in s. 251(2) to include “individuals connected by blood relationship, marriage or common-law partnership or adoption”. The 25% cross-holding is not control; it is a minority stake.
Hence the question between spouses and siblings. Treadstone Law covers spouses with separate companies (“Separate ownership by each spouse doesn’t automatically avoid association”) and sibling-controlled corporations; its answer on minority shareholdings notes association “isn’t limited to majority or controlling ownership situations.”
SECTION 03 OF 08
Section 256(1.2) supplies deeming rules. Paragraph (c) deems control where shares “having a fair market value of more than 50% of the fair market value of all the issued and outstanding shares” are owned by the other person — a value test, not a votes test, which a non-voting freeze preference can carry. Paragraphs (d) and (e) look through holding corporations and partnerships proportionately, so an intervening entity does not break the chain.
Section 256(5.1), marginal note Control in fact, catches influence without ownership: control exists where “the controller has any direct or indirect influence that, if exercised, would result in control in fact of the corporation”, subject to a carve-out for arm’s-length franchise, licence, lease, supply or management agreements.
Section 256(1.4) matters most in acquisitions, where agreements are full of unexercised rights. A person with a right, “either immediately or in the future and either absolutely or contingently”, to acquire shares or “to control the voting rights of shares” is “deemed to own the shares at that time”. An earnout option, a call over retained equity or a lender’s pledge with a voting proxy can each deem control before a share moves.
SECTION 04 OF 08
The bite is in s. 125(2): a corporation’s business limit “is $500,000 unless the corporation is associated in the taxation year with one or more other Canadian-controlled private corporations, in which case… its business limit is nil.”
Nil is the default. Subsection (3) restores it only if all the associated CCPCs “file with the Minister in prescribed form an agreement that assigns… a percentage to one or more of them”, and only where the percentages total 100% or less; otherwise, “in any other case, nil.” A group that cannot agree loses the deduction outright. Treadstone Law states the result in its answer on splitting the $500,000 limit and the policy in a companion answer: the rule stops anyone “simply setting up multiple corporations to multiply access to the lower small business rate.”
Section 125(1) allows a deduction of “the corporation’s small business deduction rate… multiplied by the least of” three amounts, one being the business limit, and subsection (1.1)(c) fixes that rate after 2018 at 19%. But what the limit is worth is the rate gap, not the deduction, because income eligible for the deduction does not also get the general tax reduction. CRA’s published rates (page updated 30 May 2025) give a federal net rate of 9% inside the limit against 15% above it, and Ontario lower and higher rates of 3.2% and 11.5% — 12.2% against 26.5%, or roughly $71,500 a year on a full $500,000 limit, for as long as the control relationship lasts.
SECTION 05 OF 08
Two rules cut the limit before you get to sharing it, and both are computed across the group. The taxable capital grind in s. 125(5.1)(a) reduces it by A × B ÷ $90,000, where B is “0.225% × (C – $10 million)” and, for an associated corporation, C is the total taxable capital employed in Canada “of the corporation or of any of the particular corporations”. So the limit erodes once combined taxable capital passes $10 million and is gone at $50 million — as Treadstone Law puts it, for a group “the combined taxable capital across the whole group is what counts”.
The passive-income grind in s. 125(5.1)(b) works identically: D/$500,000 × 5(E − $50,000), where E totals the adjusted aggregate investment income “of the corporation, or of any corporation with which it is associated”. Combined investment income over $50,000 starts the reduction; at $150,000 the limit is gone. A cash-rich holdco harmless on its own can eliminate the target’s deduction — the mechanic Treadstone Law describes here.
SECTION 06 OF 08
Section 256(2) extends association through an intermediary: two corporations are deemed associated where each is associated with “the same corporation”. Association is transitive: a group assembled one deal at a time can associate companies with no direct link.
Section 256(2.1) is the backstop: where “one of the main reasons for the separate existence of those corporations… is to reduce the amount of taxes that would otherwise be payable”, they “shall be deemed to be associated”. Treadstone Law’s answers on structuring to avoid association and different shareholders on paper note that CRA looks at “actual control and the real relationships between the people involved”.
SECTION 07 OF 08
Return to four words in s. 256(1): “at any time in the year”. Association is not prorated by the provision that creates it: a 20 December closing associates the corporations for a taxation year that began the previous January.
What does change the arithmetic is the taxation year. Acquiring control is a loss restriction event under s. 251.2(2)(a) — “control of the corporation is acquired by a person or group of persons” — and s. 249(4) deems the year “to end immediately before that time”. The target gets a short year, and s. 125(5)(b) prorates the limit of a corporation with a year “less than 51 weeks” by days over 365. Treadstone Law on becoming associated partway through a year warns the calculation “isn’t as simple as splitting the limit evenly by months.”
This belongs in the deal model, not the year-end return. Where the vendor retains an interest, or co-investors bring their own corporations, the s. 125(3) percentages are a live commercial term — better settled in the purchase agreement than after the Minister’s 30-day notice under s. 125(4).
SECTION 08 OF 08
Section 256 runs to roughly 9,000 words; this covers only the parts a buyer of a private company routinely meets. Left out: the specified class definition in s. 256(1.1), which removes certain fixed-value preference shares from the 25% count; the saving provision in s. 256(3) for control taken to safeguard a creditor’s rights; the third-corporation election in s. 256(2)(b)(ii), which buys the other two out of association at the cost of the third corporation’s own limit; and the rules on simultaneous control and acquiring control.
It addresses the federal limit only, and provinces set their own: the same CRA table lists Nova Scotia at $700,000 and Saskatchewan and Prince Edward Island at $600,000, and excludes Quebec and Alberta, which administer their own corporate tax. Association also reaches beyond section 125, including the SR&ED expenditure limit. Treadstone Law on holdco purchases covers buying through a new corporation but does not deal with association or the deduction at all.
The rule of thumb: if you or a related person will control both companies after closing, assume association and price it, then take advice on whether an exception applies.
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