Canadian buybacks: the paid-up capital sentence that decides the trade

Albert Gasull, editor · updated 17 September 2026

When a Canadian company buys its own shares outside the open market, the tax rules split the price in two. The part above the share’s paid-up capital (PUC) is a deemed dividend, and for a non-resident that dividend is withheld at 25%, reduced to 15% under most treaties. If PUC sits far below the offer price, the withholding can be a multiple of the spread. If PUC sits above the price, no deemed dividend arises. The offer document gives the PUC figure in one sentence of its tax section, and that sentence decides whether the trade works for a given account.

How the mechanism works

The company makes an issuer bid: an offer to buy back its own shares outside the open market, often a modified Dutch auction with an odd-lot clause.
Each share carries a paid-up capital figure, worked out for the whole class of shares. It is not what the holder paid.
Deemed dividend = purchase price − paid-up capital per share. If PUC is at or above the purchase price, there is no deemed dividend.
For a non-resident, the deemed dividend is withheld at 25%, or 15% under most treaties, before the cash arrives.
A sale in the market is not a purchase by the company, so it creates no deemed dividend. That is why the Air Canada circular says holders who want capital-gains treatment should consider selling in the market instead of tendering.

Who pays it

Canadian registered accounts (RRSP, TFSA). No tax on the deemed dividend; the full spread stays in the account.
Canadian taxable individuals. The deemed dividend is designated eligible. For many holders that is no worse than a capital gain, but it is taxed differently and the result depends on the holder’s own bracket.
US IRAs and other exempt retirement plans. Article XXI of the Canada–US treaty exempts them from Canadian withholding on dividends, so the trade works as printed, provided the custodian actually applies the exemption.
Everyone else taxable, US taxable accounts included. 15% of (price − PUC) is withheld, 25% without a treaty. Because the US treats the proceeds as a sale, claiming the Canadian tax as a foreign tax credit is not straightforward.

The sentence to look for

It sits in the income tax section of the circular (in Air Canada’s, Section 11, “Income tax considerations”) and reads like boilerplate:

“the paid-up capital per Share is not less than approximately $X”

X is then set against the bottom of the price range. PUC above the range: clean, no deemed dividend. PUC below the floor: the deemed dividend is almost the whole purchase price, and for a foreign taxable account the withholding is usually a multiple of the spread. None of this depends on how good the deal is. It is arithmetic, and it is one sentence deep.

Worked example: Air Canada against Arbutus

Air Canada’s offer is a C$800m modified Dutch auction between C$29.00 and C$33.00, about 27.6m shares or 9.8% of the count, expiring 24 September 2026 at 17:00 New York time, with the standard odd-lot clause. The stock traded near C$28, below the floor. The account behind issue #2 is a non-resident taxable one.

The buy: 99 shares filled at C$28.03, which is C$28.04 a share including commission.
The spread at the floor: C$29.00 − C$28.04 = C$0.96 a share, or 3.4%. At the C$33.00 ceiling it would be 17.7%.
The PUC sentence: Air Canada puts paid-up capital at approximately C$10.60 a share.
Deemed dividend at the floor: C$29.00 − C$10.60 = C$18.40.
Withholding at the 15% treaty rate: 15% × C$18.40 = C$2.76 a share, nearly three times the C$0.96 spread.
Result on 99 shares at the floor: 99 × (C$29.00 − C$28.04 − C$2.76) = −C$178.

Clears at	Deemed dividend	Tax at 15%	Result on 99 shares
C$29.00, the floor	C$18.40	C$2.76	−C$178
C$29.50, last year’s pattern	C$18.90	C$2.84	−C$136
C$31.12, break-even	C$20.52	C$3.08	C$0

Break-even needs a clearing price of C$31.12, 7% above the floor. Air Canada’s 2025 bid, with a range of C$18.50 to C$21.00, cleared at C$18.80: 1.6% above its floor. The same pattern here gives about C$29.50. The 99 shares were sold in the market on 11 September at C$27.80, a realised loss of C$24.95 after both commissions, about 0.9%.

Arbutus Biopharma is a Canadian company too, with the same structure: a modified Dutch auction between US$5.00 and US$5.75, with an odd-lot clause. Its offer document states paid-up capital of at least C$8.42 a share, above the upper end of the US$ range once converted. No deemed dividend arises. Same country, same structure, and the tax sentence goes the other way.

Editor’s view: that reversal is the reason to find the sentence in every Canadian circular rather than assume it.

Where it goes wrong

Pricing the spread before reading the tax section. Air Canada’s 3.4% at the floor becomes −C$178 on 99 shares for a non-resident taxable account.
Treating one Canadian bid like the next. Air Canada and Arbutus share a country and a structure, and get opposite answers.
Counting on a high clearing price. Break-even at Air Canada needs a price 7% above the floor; the 2025 bid cleared 1.6% above its floor.
Assuming an exemption is applied. A US IRA is exempt under Article XXI only if the custodian actually applies it.

How to check it

The income tax section of the circular prints a paid-up capital figure per share.
That figure sits above or below the floor of the price range, once both are in the same currency.
The account statement shows which group the account belongs to: Canadian registered, Canadian taxable, US exempt retirement plan, or other taxable.
The custodian’s dividend records show the withholding rate applied to Canadian dividends, and whether a treaty exemption is applied.
The tax section also says how a sale in the market is treated, next to a tender.

Sources

Air Canada — issuer bid terms, 17 Aug 2026
Arbutus ABUS — SEC Schedule TO-I filings
99 Shares — issue #2, 14 September 2026, with its correction dated 17 September 2026

Next guide: Broker cutoffs and record dates: the dates that decide a tender

Author holds: Air Canada, no (sold 11 September 2026); Arbutus, yes, 99 shares (17 September 2026). 99 Shares is information, not advice, and tax treatment depends on where the holder and the account live. Terms of use.