Why you can still owe the IRS after paying Canadian tax

I pay more tax in Canada: why does my US return still show tax due?

A US citizen living in Canada remains subject to US tax on worldwide income. Canadian federal and provincial income tax reduces regular US income tax through a foreign tax credit. A balance appears when the US tax on a category of income is more than the Canadian tax the US will credit against it. The comparison runs category by category, not against your total Canadian bill. IRS Publication 597, Form 1116 instructions, Foreign Taxes Eligible for a Credit.

A shortfall in withholding or estimated payments is a separate cause. These usually explain a balance on investments:

The worldwide-income rule also applies to a green card holder who remains a US tax resident. The treaty’s special credit rules in Article XXIV(4)–(6) apply only while a US citizen is a resident of Canada, so a change of residence changes the result and a green card holder needs a separate check. IRS Publication 597.

Why does the US not credit all Canadian tax on my US dividends and interest?

On a US dividend, the US keeps a protected amount of tax and Canada credits only that amount. The US then credits Canadian tax above it, but only up to the extra US tax on the dividend. US tax up to the protected amount is therefore not offset by Canadian tax, even when your Canadian bill is higher. Article XXIV(4)–(6).

The protected amount is what the US could charge a Canadian resident who was not a US citizen, and the rule applies only while Canadian law lets you deduct foreign tax above the treaty rate. To let the US credit the rest, the treaty treats part of the dividend as if it came from Canada (re-sourcing), but only the income needed for the additional credit; living in Canada does not make every US investment payment foreign-source. Article XXIV(5)–(6), Publication 514, Tax Treaties.

Dividends and interest have different starting points:

For ordinary US-source interest the treaty leaves no protected US amount: the US credits Canadian tax on that interest against its own tax on the same interest, within the credit limit. A balance linked to interest therefore usually comes from Canadian tax that is lower than US tax on it, a category or timing mismatch, or net investment income tax, not from the dividend rule above. Article XXIV(3), (4) and (6), Publication 514, Tax Treaties.

These are treaty allocation rules, not a cap on a US citizen’s final tax: the saving clause preserves citizenship taxation. Articles X and XI, IRS Publication 597. The Canadian side is covered in Foreign income on a Canadian return.

Example

Illustrative only. All amounts are in US dollars, including converted Canadian tax. Assume a US citizen resident in Canada receives US$10,000 of ordinary US corporate dividends. The allocated regular US tax before foreign credits is US$2,000; Canadian tax before its foreign credit is US$3,000. Ignore other income, deductions, carryovers, net investment income tax and prepayments.

Treaty re-sourcing enables the additional US$500 credit; the US$1,500 source-country amount remains payable to the US. Combined regular tax is US$3,000, split evenly only because of these assumed numbers. Canada’s pre-credit tax was higher, yet US$1,500 is still payable to the IRS.

This simplified sequence follows Article XXIV(5)–(6) and the Publication 514 additional-credit worksheet. Ordinary interest follows a different rule, described above.

Why can’t Canadian tax on wages or business income cover my investments?

The US figures the credit separately for wages and for investment income, so extra Canadian tax on your salary cannot be used against US tax on your investments. The IRS calls these pools categories. Wages usually fall in the general category; ordinary dividends, interest and investment gains usually fall in the passive category. Active business income can require a different category depending on how the business operates. Form 1116 instructions, Categories of Income.

One exception: if the foreign tax on an item of investment income is more than the highest US tax that can be imposed on it, the IRS calls it high-taxed income and moves it out of the passive category. For a US citizen resident in Canada, dividends re-sourced under Article XXIV stay in the passive category, not the separate treaty category used for other re-sourcing (26 CFR 1.904-4(k)(1)(iv)(A)). Foreign income on a US return covers how each item’s category is set. Form 1116 instructions, Passive Category Income and Certain Income Re-Sourced by Treaty.

Why does the IRS charge net investment income tax after my credit?

Foreign tax credits reduce only regular US income tax. Net investment income tax (NIIT) is a separate tax under a different part of the Code, so a foreign tax credit cannot reduce it. 26 CFR 1.1411-1(e), IRS NIIT questions and answers, question 17.

NIIT applies at 3.8% to the smaller of net investment income, such as interest, dividends and capital gains, or modified adjusted gross income above the filing-status threshold. A large sale can therefore leave this tax even when credits eliminate regular US income tax. IRS: Net investment income tax.

Modified adjusted gross income generally adds back excluded foreign earned income, so wages you exclude still count toward the threshold. IRS: NIIT questions and answers, question 4.

A spouse who is not a US citizen or green card holder can change your filing status, and so your threshold; see Americans living in Canada. If you deduct foreign income tax (Schedule A) instead of crediting it, you generally deduct all of that year's foreign income taxes and claim no credit, and some or all of the deduction may reduce net investment income. Publication 514, Choosing To Take Credit or Deduction, IRS: NIIT questions and answers, question 17.

In Estate of Bruyea v. United States, No. 2025-1563 (Fed. Cir. Aug. 31, 2026), the Federal Circuit held that neither the Internal Revenue Code nor Article XXIV of the Canada treaty allows a foreign tax credit against net investment income tax. It reversed a judgment for a US citizen in Canada who had paid Canadian tax on a sale of real estate there. Courts considering comparable claims under other treaties have reached the same result. Rehearing can be sought within 45 days of judgment when the United States is a party (Federal Circuit Clerk), and Supreme Court review within 90 days of judgment or of a rehearing denial (Federal Circuit Clerk). Either could still change the outcome.

A return that takes a treaty-based credit against this tax goes against that holding. The IRS requires a treaty-based credit that the Code does not allow to be disclosed on Form 8833 with the return, and the penalty for not disclosing is US$1,000 per failure, so the position needs separate review before filing. Publication 514, Tax Treaties, 26 U.S.C. 6712.

My TFSA grows tax-free in Canada: why can the IRS tax it?

Because the US has no matching exemption. Canada generally does not tax TFSA interest, dividends or capital gains (CRA: What is a TFSA). A US citizen is taxed on worldwide income whatever the other country does (26 CFR 1.1-1(b)), the treaty’s saving clause keeps that rule (IRS Publication 597), and its deferral for Canadian plans covers only plans operated exclusively to provide pension or employee benefits (Article XVIII(7)). Income inside a TFSA is therefore generally taxable on the US return as it is earned, with no Canadian tax to credit.

Interest, dividends and gains paid or realised inside the account are generally income; a rise in value you have not realised is generally not, unless a special regime such as the passive foreign investment company rules applies. Whether a TFSA is also a foreign trust is unsettled. For that, and for RRSPs, RESPs and other registered accounts, see Canadian registered accounts on a US return.

Can Canada’s dividend credit or capital gains rule lower the tax available to credit?

Yes. Canadian relief can reduce the actual Canadian tax on an investment, even when your overall Canadian tax rate looks high. The US credit starts with qualifying tax actually paid or accrued after applicable reductions, not the tax that Canada would have charged without its credits. Form 1116 instructions, Foreign Taxes Not Eligible for a Credit.

Where the Canadian tax on your investment income is lower than the US tax on it, the US credit stops at the Canadian amount and the difference stays payable to the IRS, however high your Canadian marginal rate looks. CRA: Federal dividend tax credit, Income Tax Act, section 38.

Can unused Canadian tax carry to other US tax years?

Eligible foreign tax over the US credit limit can generally carry back 1 year and then forward 10 years, within the same income category and the credit room of the receiving year. The period does not extend just because you cannot use the credit. Choosing a deduction, or the election to claim a credit without Form 1116, can also restrict carryover use. Form 1116 instructions, Line 10, Publication 514, Carryback and Carryover.

Which US year can use Canadian tax depends on whether you claim foreign tax when paid or when accrued, so Canadian tax for one year can land in a different US year. A cash-method filer can choose accrual by checking "Accrued" in Part II of Form 1116 on a timely filed original return; the choice covers all foreign taxes and binds later years. Publication 514, Credit for Taxes Paid or Accrued. A later Canadian refund or reassessment can require a change to the US return; see Amending your return after the other country changes yours.

Would the foreign earned income exclusion or a deduction fix this?

The foreign earned income exclusion does not exclude ordinary dividends, interest or investment gains. Deducting foreign tax changes taxable income rather than supplying the same direct tax reduction as a credit. Canadian income tax allocated to excluded earnings cannot also be credited or deducted. Publication 54, Publication 514.

Choosing between the exclusion, a credit and a deduction is covered in Americans living in Canada and Foreign income on a US return.

What can I do about it going forward?

A projection of both returns before a large sale shows the credit and NIIT result. NIIT is figured year by year, so the year a gain is recognised can change whether the threshold is passed. A projection needs the purchase cost and date, the expected sale price, your other income in both currencies, and any carryovers.

After a balance appears:

1. Find the cause. Match it to a row in the table at the top.
2. Check the credit. See whether it was limited by category, the treaty cap or a carryover.
3. Estimate NIIT. Include it when your income is above the threshold.
4. Compare liability with payments. Set total US liability against withholding and estimated payments; insufficient estimated payments can bring a penalty. IRS: Net investment income tax.

When should a cross-border preparer run both returns together?

One country’s credit changes the tax available for the other country’s credit. US-source investment income, a large sale, expiring carryovers, registered accounts or a treaty-based filing position are reasons to calculate both returns together before filing or transacting.

Bring both full returns and credit worksheets, the Canadian slips and notices of assessment, US investment statements, proof of tax paid, carryover schedules, and any IRS or CRA letter. For its foreign tax credit the CRA lists official receipts of foreign tax paid and, for US tax, the US return and US tax account transcript as supporting documents (CRA: Federal foreign tax credit). The full checklist, and which return to file first so credits match, are in When you need a cross-border accountant.

Different for you?

• US-source dividends, a large sale, expiring credits, or a return position that depends on a treaty credit against net investment income tax: see cross-border tax preparation.
• An IRS letter proposing more tax on your investments: see Answering an IRS letter while living in Canada. A CP2000 states its own reply date; a notice of deficiency allows 90 days to petition the Tax Court, or 150 days if addressed outside the United States (26 U.S.C. 6213).
• A green card, or doubt about whether you are still a US tax resident: see Filing US taxes while living abroad.
• A TFSA, RRSP, RESP or another registered account: see Canadian registered accounts on a US return.
• Different gains on the two returns: see Selling investments as an American in Canada.
• Canadian mutual funds or ETFs: see Funds bought outside the US.
• Missing earlier US returns: see Catching up on missed US returns.