Canadian Founders Selling US Startup Shares

Does the US tax a Canadian founder's gain just because the company is American?

No. This guide assumes you sell your shares. If the company instead sells its assets and pays shareholders, those are separate transactions (IRS). For a person resident in Canada under the Canada–US treaty, Article XIII, gain from ordinary US company shares is generally taxable only in Canada. US incorporation alone does not give the US taxing rights over the share gain.

Check the seller and the shares before relying on that rule:

If the shares are a US real-property interest, check FIRPTA withholding and any withholding certificate before closing. The buyer generally withholds 15% of the amount realized and files Forms 8288 and 8288-A within 20 days after transfer (IRS instructions); the seller reports the gain on the applicable US return.

US presence can affect residence. A separate rule for some nonresidents present for at least 183 days applies only to certain US-source capital gains; it does not make an otherwise foreign-source share gain US-source (IRS Publication 519). Test source and treaty residence first. US state tax may differ from the federal treaty result.

When could the US small-business stock exclusion help?

Section 1202 matters only when the US can tax your gain and the eligible taxpayer is not a corporation. It can also apply to certain gains passed through an eligible entity. It cannot reduce a Canadian tax bill. The statute excludes eligible gain from a noncorporate taxpayer's US gross income, subject to stock tests and a per-issuer limit.

Stock acquired on or before July 4, 2025 generally needs more than five years; its exclusion share depends on the acquisition date. Current law gives later-acquired stock shorter minimum holding periods, but that stock cannot yet reach them during this guide's tax year. The published Schedule D instructions still describe the older rule.

The issuer, original-issue, active-business, redemption, hedge and holding-period tests need their own review; see LLC or C corporation. If a US LLC is becoming a C corporation, the conversion and share-issuance dates can change the result; see Changing your business structure. The section 1202 exclusion is disregarded under Publication 519's separate nonresident capital-gain rule (IRS).

If the US can tax a sale before the exclusion's holding period, section 1045 may defer US gain on qualifying stock held more than 6 months. The seller buys replacement qualified stock within 60 days and elects by the US return due date, including extensions; a timely original return may be amended within 6 months of the unextended due date (IRS Publication 550). Canada calculates its gain separately.

Will Canada tax the gain if the US excludes it?

Yes, if you are Canadian resident when you sell and the shares are capital property, calculate the Canadian gain independently. Canada's capital-gain calculation starts with sale proceeds, less adjusted cost base and selling costs. The general taxable portion is 50% under section 38, before applicable capital losses. Provincial tax also depends on where you reside.

Section 1202 changes US gross income, not the Canadian proceeds or cost of your US shares. If the treaty permits US tax on the gain, Canada may allow a credit for qualifying US tax. If the US taxes ordinary share gain solely because the seller is a US citizen resident in Canada, Article XXIV generally places relief on the US return through a credit for Canadian tax, subject to limits. See Foreign income on a Canadian return for the Canadian claim.

Can I claim Canada's lifetime capital gains exemption on US founder shares?

No, shares of a US C corporation do not qualify as Canadian qualified small business corporation shares. The Canadian capital gains deduction rules require qualifying shares of a Canadian-controlled private corporation. Building a US business from Canada does not turn its US-issued shares into those shares.

The US section 1202 exclusion and Canada's lifetime capital gains exemption are separate rules. Neither transfers to the other country's return.

What if I bought the shares before moving to Canada?

For ordinary US shares you owned when you became Canadian resident, Canada's starting cost is generally their fair market value at that time, not your earlier US purchase price. Income Tax Act section 128.1 deems most property sold and reacquired at fair market value on immigration. The US basis does not automatically change to that Canadian value.

Calculate the Canadian gain in Canadian dollars. Convert sale proceeds at the sale-date rate, adjusted cost base at the acquisition-date rate, and selling costs when paid (CRA). For shares deemed reacquired on immigration, record the value in Canadian dollars on that date. Currency movement after that date can change the Canadian gain even when the US-dollar share price barely moves.

Keep the valuation method and evidence for the immigration date. Track each grant's dates for the US stock tests. For Canada, average the Canadian-dollar cost of identical shares of the same class when calculating adjusted cost base, unless an exception applies (CRA). For shares acquired through employee options after immigration, add any option benefit included in Canadian income to the purchase price; shares already owned at immigration start at their immigration-date value (CRA; Income Tax Act). See Stock awards and pay after a move for cross-border award timing.

What if my Canadian corporation owns the founder shares?

The Canadian corporation sells its own shares and reports its own gain; you do not report that sale as a personal share gain. Section 1202 expressly applies to a taxpayer other than a corporation, so your Canadian corporation cannot claim it (26 USC 1202).

The corporation generally reports a capital-property disposition on its Canadian T2 and Schedule 6 (CRA T2 guide). If the US company is its foreign affiliate, the Canadian corporation can elect under section 93(1) to treat an elected part of the gain as a foreign-affiliate dividend; the Canadian result then depends on its surplus. File Form T2107 by the T2 due date, six months after year-end (regulation 5902(5)).

A later dividend or other payment from the holding corporation to you is a separate transaction. If it transfers sale proceeds to a related shareholder for less than fair value, section 160 can make the recipient jointly liable for the lesser of the value shortfall and the corporation's tax debt for that or an earlier year, even if assessed later; the CRA may assess the recipient at any time. For a corporate owner, test treaty residence and Article XXIX A eligibility, US business connection, and Canadian foreign-asset filings. Use cross-border tax before a holding-company sale or reorganization.

What if I move to the US before the sale or am a US citizen in Canada?

A move or US citizenship can make the US tax computation central. The treaty preserves US taxation of its citizens and residents, while its double-taxation article coordinates credits. If you qualify for section 1202 as an individual, test it against your US gain and actual stock history; it still does not erase a Canadian gain arising while you were resident here.

For a US citizen resident in Canada, the US generally gives relief for Canadian tax on ordinary share gain taxed solely because of citizenship, subject to credit limits (Article XXIV).

Leaving Canada while holding the shares can cause a Canadian deemed sale before the actual exit. Shares owned when you last became Canadian resident are excepted if you lived in Canada for no more than 60 months in the preceding 120 months (section 128.1(4)(b)(iv)). If departure tax applies, an individual may defer payment by electing on Form T1244 by April 30 of the year after departure (section 220(4.5)); see Leaving Canada. If Canada taxes the deemed sale, the individual can make the treaty's Article XIII(7) election to treat the shares as sold and reacquired for US tax by attaching Form 8833 to a timely US return for the first tax year ending after the move; see Moving from Canada to the US. For a US citizen who remains in Canada, the Americans living in Canada guide covers the two personal returns.

What do I report, and what records should I keep?

The seller reports the disposition in its country of residence; a US return depends on US tax status and whether the US can tax the gain. Keep both countries' basis calculations even if one country allows an exclusion.

For a Canadian resident who is neither a US citizen nor a US tax resident, an ordinary share sale taxable only in Canada generally does not itself require Form 1040-NR; other US income or activity can (IRS). If a broker requests foreign-status documentation, an individual generally gives Form W-8BEN and a Canadian corporation Form W-8BEN-E to the broker (IRS Publication 515).

Owning US shares can also trigger Canadian foreign-property or foreign-affiliate information forms. An individual need not file Form T1135 for the year they first become Canadian resident (CRA); see Foreign property and affiliate reporting.

Keep the share subscription and option or restricted-stock agreements, issuance and exercise dates, proof of payment or compensation, cap table and changes in ownership, issuer asset and activity records, immigration-date valuation, exchange rates, sale agreement, closing statement and selling costs. These records establish who sold, what was sold, when the holding period began, and each country's cost.

Example

Illustrative amounts in Canadian dollars, with no selling costs or other gains or losses. A founder bought US company shares before moving to Canada. At immigration, the shares were worth C$200,000. The founder sells them while resident in Canada for proceeds worth C$600,000. Canada's capital gain is C$400,000; at a one-half inclusion rate, C$200,000 is taxable before any applicable losses. If the treaty gives the US no right to tax the ordinary share gain, section 1202 does not change either Canadian amount. The original US purchase cost remains relevant if the US later has a taxable gain.

Different for you?

• You are about to sign an exit agreement, have unusual share rights, or hold shares through a corporation: the seller and gain type can change. Get cross-border tax help before closing.
• Your US LLC is converting before a share sale: see Changing your business structure.
• You are leaving Canada with the shares: see Leaving Canada and Moving from Canada to the US.
• You are a US citizen living in Canada: see Americans living in Canada.
• The treaty permits US tax on the gain: see Foreign income on a Canadian return.