The 3.8% Net Investment Income Tax for US Citizens in Canada

By Yarik Yarosh, CPA ·August 21, 2026 ·Updated September 23, 2026 ·9 min read

Written by Yarik Yarosh, CPA (US & Canada) August 21, 2026 · FL CPA license AC61704 · CPA Ontario

The 3.8% Net Investment Income Tax under IRC 1411 hits US citizens in Canada harder than it hits US citizens in the US, because the foreign tax credit that absorbs Canadian tax on your regular return does not apply to the NIIT. The NIIT is a separate tax, and the FTC under IRC 901 does not offset it. Canadian tax you paid on the same investment income sits on one side, the NIIT sits on the other, and neither reduces the other. The result is genuine double taxation on investment income, with no credit to prevent it.

✓Key takeaway

The NIIT applies to the lesser of your net investment income or the amount by which your modified adjusted gross income (MAGI) exceeds the threshold ($200,000 single, $250,000 married filing jointly). The FTC under IRC 901 does not apply to the NIIT because the NIIT is not a tax under Chapter 1 of the Internal Revenue Code (it is in Chapter 2A), and the FTC is a Chapter 1 credit. Canadian tax paid on investment income offsets your regular US income tax on that income but does not touch the NIIT. You pay both. Treasury received comments requesting a foreign tax credit against the NIIT during the 2013 rulemaking (REG-130843-13), but explicitly rejected the approach in the final regulations (TD 9644), codifying the prohibition in Reg. 1.1411-1(e). The proposed regulations reserved a section for potential future guidance on crediting foreign taxes against the NIIT (proposed Reg. 1.1411-4(g)(5)), but no guidance has been issued.

What’s the NIIT?

The Net Investment Income Tax was enacted by the Affordable Care Act (2010), effective for tax years beginning after December 31, 2012. It imposes a 3.8% tax on the lesser of:

Net investment income, or
The excess of MAGI over the applicable threshold

The thresholds are:

$200,000 for single filers
$250,000 for married filing jointly
$125,000 for married filing separately

Net investment income includes interest, dividends, capital gains, rental income, royalties, non-qualified annuities, and income from passive activities. It does not include wages, self-employment income (which is subject to the 0.9% Additional Medicare Tax instead), distributions from qualified retirement plans (IRAs, 401(k)s), or tax-exempt interest.

The tax is reported on Form 8960, Net Investment Income Tax.

Why does the FTC not offset it?

Because of where the NIIT sits in the Internal Revenue Code. The FTC under IRC 901 is a credit “against the tax imposed by this chapter,” and “this chapter” is Chapter 1 (the regular income tax). The NIIT is codified in Chapter 2A (IRC 1411). The FTC applies to Chapter 1 taxes only. Treasury received comments requesting a foreign tax credit against the NIIT during the 2013 rulemaking (REG-130843-13), but explicitly rejected the approach in the final regulations (TD 9644), codifying the prohibition in Reg. 1.1411-1(e). The proposed regulations reserved a section for potential future guidance (proposed Reg. 1.1411-4(g)(5)), but none has been issued. As of 2026, no credit is available.

The practical result: a US citizen in Canada who earns investment income pays Canadian tax on it (via the T1), claims an FTC on the regular US return (Form 1116) for the Canadian tax, and then pays the 3.8% NIIT on top, with no offset. The Canadian tax reduces the regular US income tax to zero (or near zero, given higher Canadian rates), but the NIIT remains in full.

How does it work in practice?

Consider a US citizen in Ontario with $300,000 of MAGI (married filing jointly) and $80,000 of net investment income from a non-registered brokerage account. The regular US income tax on that investment income is effectively zero: Canadian tax at Ontario’s combined rate is claimed as an FTC on Form 1116, and because Canadian rates exceed the US rate, the FTC wipes out the regular US tax entirely.

NIIT calculation: MAGI ($300,000) exceeds the MFJ threshold ($250,000) by $50,000. Net investment income is $80,000. The NIIT applies to the lesser: $50,000. Tax: 3.8% of $50,000 = $1,900. No FTC available. The $1,900 is owed in addition to the Canadian tax already paid.
Result: the $1,900 is pure double taxation. Canada does not credit the NIIT (CRA does not recognize it as an income tax creditable under ITA 126), and the US does not credit the NIIT for Canadian tax.

Hypothetical example

A hypothetical with made-up numbers. A US citizen in British Columbia earns $180,000 from employment and $120,000 from non-registered investments (dividends, interest, capital gains). Total MAGI: $300,000. Filing single.

Regular US income tax on the investment income: effectively zero after the FTC for BC combined federal-provincial tax.

NIIT: MAGI ($300,000) exceeds single threshold ($200,000) by $100,000. Net investment income: $120,000. NIIT applies to the lesser: $100,000. Tax: $3,800.

She paid approximately $30,000 in Canadian tax on the investment income (various rates depending on the type). She claimed that as an FTC, zeroing out the regular US tax. But the $3,800 NIIT sits on top.

Her effective rate on the investment income is the Canadian rate plus 3.8% on a portion, with no mechanism to credit one against the other.

If her MAGI were $200,000 or below (as a single filer), the NIIT would be zero regardless of how much investment income she had, because the excess over the threshold is zero. The MAGI threshold is the gatekeeper: high-income filers pay it, lower-income filers do not.

Change the facts. She has no investment income (all employment income). Net investment income: $0. NIIT: $0. The NIIT only applies to investment income, not wages. Her Canadian employment tax is fully handled by the FTC on the regular return.

Illustrative numbers only, not a real client and not advice for your facts.

What about RRSP distributions?

RRSP distributions are not excluded from net investment income under the NIIT statute. IRC 1411(c)(5) excludes distributions from plans described in sections 401(a), 403(a), 403(b), 408, 408A, and 457(b), all of which are US plan types. A Canadian RRSP is not described in any of those sections. The treaty election under Article XVIII(7) preserves the RRSP’s tax-deferred status for regular US income tax purposes, but it does not reclassify the RRSP as a plan described in those Code sections for NIIT purposes. RRSP distributions received by a US person whose MAGI exceeds the threshold could therefore be subject to the NIIT.

US-side 401(k) and IRA distributions remain excluded from the NIIT under IRC 1411(c)(5), but RRSP distributions do not get the same treatment.

What about TFSA income?

If the TFSA is treated as a foreign trust and its annual income is reported on the US return, that income may be net investment income for NIIT purposes. Interest, dividends, and capital gains inside the TFSA are investment income. If the US citizen’s MAGI is above the threshold, the NIIT applies to the TFSA income, on top of the regular US tax and the Canadian tax-free treatment. This is another reason not to open a TFSA if you are a US citizen in Canada: the NIIT adds 3.8% on top of the regular US tax on income that Canada treats as tax-free.

Can I reduce the NIIT?

The NIIT is based on MAGI and net investment income. Reducing either reduces the tax.

Reduce MAGI: RRSP contributions reduce Canadian taxable income but do not reduce US MAGI (the treaty election defers taxation but does not create a deduction). RRSP contributions do not help with the NIIT.
Reduce net investment income: harvesting capital losses reduces NII. Choosing investments that defer recognition (unrealized gains) reduces current-year NII. Note that shifting investments into an RRSP defers Canadian tax, but RRSP distributions are not excluded from NII under IRC 1411(c)(5) (that exclusion covers only US plan types), so the NIIT exposure may reappear on withdrawal.
Stay below the threshold: for a single filer at $200,000 of MAGI, the NIIT is zero regardless of investment income. Income timing and deferral strategies that keep MAGI below the threshold in a given year eliminate the NIIT for that year.

Practitioner note

The NIIT is the tax that produces the sharpest double taxation for US citizens in Canada, because there is no credit against it on either side. Most other double-taxation scenarios are resolved by the FTC or by treaty provisions. The NIIT sits in a gap that commenters asked Treasury to close in the 2013 rulemaking, and Treasury declined (TD 9644, Reg. 1.1411-1(e)). The practical impact depends on income level and investment mix. For a US citizen in Canada with employment income under $200,000 and minimal investment income, the NIIT may be zero. For a US citizen with a large non-registered portfolio generating dividends and capital gains, the NIIT is a persistent annual cost with no offset. It is one of the inputs into the “should I hold investments in registered vs non-registered accounts” decision. Note that while RRSP contributions defer Canadian tax and move income out of the current-year non-registered portfolio, RRSP distributions are not excluded from NII under IRC 1411(c)(5) (that exclusion lists only US plan types), so the NIIT exposure may shift to the withdrawal year rather than disappear.

What should I do next?

Calculate your MAGI and net investment income. If MAGI is below the threshold, the NIIT is not a current issue, but watch for years where capital gains or other investment income spikes push you over. If MAGI is above the threshold, quantify the NIIT and factor it into your investment strategy. Consider harvesting losses in the non-registered account to reduce current-year NII. RRSP contributions defer Canadian tax and remove income from the current-year non-registered portfolio, but RRSP distributions are not excluded from NII under IRC 1411(c)(5), so the NIIT exposure may reappear on withdrawal.

Form 1116: why isn’t my foreign tax credit dollar for dollar?, the FTC that handles regular tax but not the NIIT
FEIE or FTC? Why FTC usually wins in Canada, because the FEIE does not help with the NIIT either
I’m American and moving to Canada for the first time, where the NIIT is one of several new US obligations
Is a TFSA a foreign trust for US purposes?, because TFSA income compounds the NIIT problem

Related guides:

Net Investment Income Tax (NIIT): The 3.8% Surtax on Passive Income for Business Owners

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Cite this page

Yarik Yarosh, CPA. "The 3.8% Net Investment Income Tax for US Citizens in Canada." Blue Cloud CPA, August 21, 2026, updated September 23, 2026. https://bluecloudcpa.com/guides/niit-3-8-percent-us-citizen-canada

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.