- Paid-up capital (PUC) is a tax concept tracked by the corporation itself, for each class of shares.
- Adjusted cost base (ACB) is a completely different number, and it belongs to the individual shareholder, not the corporation.
- In a simple case — a single founder who subscribed for shares at incorporation and has never transferred them — PUC and ACB may look similar.
Two co-owners incorporate a business together. Years later, one bought their shares from a retiring founder at a premium, while the other has held theirs since day one. When the corporation finally returns some capital to its shareholders, the two owners get very different tax results from what looks like the same payment — and neither of them understands why.
The answer lies in the difference between paid-up capital and adjusted cost base. They sound like they should mean the same thing, and many business owners use them interchangeably. They don't, and the distinction is exactly what determines how much of a capital return is tax-free.
Paid-Up Capital: A Corporate, Not Personal, Number
Paid-up capital (PUC) is a tax concept tracked by the corporation itself, for each class of shares. It generally reflects the capital originally contributed for that class of shares, and — critically — it is the same figure per share within a class, regardless of who currently holds the shares or what any individual shareholder actually paid for them.
Because PUC belongs to the share class rather than to any one shareholder, a corporation can reduce its PUC and pay that amount out to shareholders as a return of capital, generally without that portion being taxed as a dividend. PUC is the corporation's own ledger of how much it can hand back this way.
Adjusted Cost Base: Personal to Each Shareholder
Adjusted cost base (ACB) is a completely different number, and it belongs to the individual shareholder, not the corporation. It represents what that specific shareholder actually paid (or is deemed to have paid, in some transactions) for their particular shares, adjusted over time for certain events.
ACB is used to work out a shareholder's capital gain or loss — whether on an eventual sale of the shares, or when a return of capital exceeds what the shareholder is treated as still having invested.
Why PUC and ACB Diverge
In a simple case — a single founder who subscribed for shares at incorporation and has never transferred them — PUC and ACB may look similar. They diverge in common, everyday situations:
- A shareholder buys shares from another shareholder. The buyer's ACB is what they paid for the shares; the class's PUC doesn't change just because ownership changed hands.
- Shares are transferred through a corporate reorganization, such as certain tax-deferred rollovers, where the transferor's cost is carried forward in ways that can differ from the class's PUC.
- Shares pass through an estate or gift, where the recipient's ACB is determined by rules specific to that transfer, again independent of the corporation's PUC.
The result: two shareholders holding an identical number of shares in the same class, with identical PUC per share, can have very different personal ACBs.
What Happens When the Corporation Returns Capital
| Scenario | General tax result |
|---|---|
| Amount returned is within PUC, and within the shareholder's ACB | Tax-free return of capital; reduces the shareholder's ACB |
| Amount returned is within PUC, but exceeds the shareholder's ACB | The excess over ACB is generally taxed as a capital gain |
| Amount returned exceeds the corporation's PUC | The excess over PUC is generally treated as a deemed dividend, not a capital return |
This is why the same per-share payment can be tax-free for one shareholder and partly taxable for another — PUC sets the outer limit on what can come out as a capital return at all, while each shareholder's own ACB determines whether their personal portion of it triggers a gain.
An Illustrative Example (Not Actual Figures)
To see how this plays out, imagine two shareholders holding identical common shares in the same private corporation, with figures chosen purely to illustrate the mechanics — not to represent any actual rate, threshold, or typical amount:
- Shareholder A subscribed for shares at incorporation. Their ACB matches the shares' PUC per share.
- Shareholder B bought the same class of shares later, directly from a retiring founder, at a meaningfully higher price. Their personal ACB per share is well above the PUC per share — even though it's the identical class of shares.
If the corporation reduces PUC and pays out an amount per share that stays within both the PUC and Shareholder A's ACB, Shareholder A receives it tax-free and simply reduces their ACB going forward. Shareholder B, having a higher ACB, is even more comfortably below their own cost — also no immediate gain. But if the corporation later pays out an amount per share that exceeds the class's PUC altogether, both shareholders would see that excess portion treated as a deemed dividend, regardless of how their individual ACBs compare.
Work through your own numbers with an accountant — the actual calculation depends on the corporation's specific PUC history and each shareholder's specific ACB, neither of which can be assumed from a general example.
Why This Matters Before You Reduce Capital
Getting this wrong isn't just an accounting inconvenience — a return of capital that unexpectedly exceeds PUC, or that a shareholder assumed was tax-free without checking their own ACB, can generate an unwelcome dividend inclusion or capital gain at tax time. Confirm both figures before the corporation makes any capital distribution, not after.
Frequently asked questions
Is paid-up capital the same as what a shareholder originally invested?
Not necessarily. PUC starts out reflecting the capital contributed for a share class, but subsequent transfers between shareholders don't change it — while each shareholder's personal cost (their ACB) can differ significantly from the class's PUC.
Can a corporation choose not to reduce PUC even if it wants to return money to shareholders?
Yes — paying out money to shareholders doesn't have to go through a PUC reduction. Money paid out that isn't structured as a capital return will generally be treated as a dividend instead, with different tax consequences.
How do I find out my corporation's current PUC per share?
This is tracked in the corporation's own tax and financial records, typically maintained by its accountant. It isn't something a shareholder can calculate independently without that history.
Does ACB ever go below zero?
It can, in specific circumstances involving successive capital returns. A negative ACB is itself generally treated as triggering a capital gain — another reason to confirm the numbers with an accountant before assuming a distribution is tax-free.
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