What is a dual-status tax year and how do I file one?

How a single US tax year ends up with two statuses

The US taxes resident aliens on worldwide income and nonresident aliens only on US-source income. A dual-status year arises when you cross from one category to the other partway through the calendar year, so each portion is taxed under its own rules. For Canadians this happens in exactly two situations: the year you move to the US, and the year you move back.

Where the dividing line falls depends on how you became a resident:

• Under the substantial presence test, your residency starting date is generally the first day you were physically present in the US during the year in which you met the test. A short visit early in the year, such as a house-hunting trip, can pull the start date forward, although up to 10 days of presence can be disregarded if you had a closer connection to Canada at the time.
• Under the green card test, residency starts on the first day you were present in the US as a lawful permanent resident.
• When you leave, your residency termination date is your last day in the US, provided you have a closer connection to Canada for the rest of the year and you attach a statement establishing it. Without that statement, residency runs to December 31.

Canada has no dual-status label, but it splits the year the same way: your T1 for the year of departure or arrival carries the date on page 1, worldwide income is reported only for the resident portion, and personal credits are prorated. The two countries' dates should match, and where they cannot, the treaty tie-breaker described in how the treaty decides which country I am a resident of settles the overlap.

Which form is the return and which is the statement

Your status on the last day of the year decides which form leads. The IRS wants one return with the other form attached, and it asks you to write the words across the top of each:

• Moved to the US (resident on December 31): file Form 1040 marked Dual-Status Return, and attach Form 1040-NR marked Dual-Status Statement showing the US-source income from before your residency start date.
• Moved back to Canada (nonresident on December 31): file Form 1040-NR as the Dual-Status Return, and attach Form 1040 as the statement for the resident months.

The resident portion picks up everything: Canadian employment income earned after the start date, Canadian investment income, and the interest in the chequing account you left behind, all with foreign tax credits on Form 1116 for the Canadian tax. The nonresident portion picks up only US-source income, such as US wages for days worked in the US before you moved. Income earned in Canada before your US residency began never appears on a US return.

Deadlines follow the lead form. A dual-status return ending in resident status is due April 15. One ending in nonresident status is due June 15 if you had no wages subject to US withholding, and April 15 otherwise. Confirm the date for your own facts rather than assuming the later one.

What dual-status filers lose, and the two elections that change the outcome

Dual-status returns come with restrictions. You cannot claim the standard deduction, so you itemize or deduct nothing. You cannot file a joint return, and you cannot use head-of-household rates. Several credits are also limited during the nonresident portion. For a couple arriving mid-year with modest itemized deductions, these rules can cost real money, which is why two elections exist:

1. The first-year choice. If you arrive late in the year and do not yet meet the substantial presence test, you would ordinarily be a nonresident for the whole year. If you will meet the test the following year, and you were present for at least 31 consecutive days and 75% of the days from then to year-end, you can elect to be treated as a resident from your arrival date. This creates a dual-status year on purpose, usually to start the clock on residency and to access the joint-filing election below.
2. The full-year resident election. A dual-status individual who is married to a US citizen or resident on December 31 can elect under section 6013 to be treated as a resident for the entire year and file jointly. The price is that worldwide income for the whole year, including the Canadian months, goes on the 1040, offset by foreign tax credits. For couples with mostly Canadian-taxed income, the standard deduction and joint brackets often more than cover the cost. We run both versions before choosing.

Neither election is automatic. Each requires a statement attached to the return, and the joint election stays in force for future years until it is revoked or ended.

The Canadian half of the same year

The Canadian side of a move year is usually the heavier return. Leaving triggers the deemed disposition on most non-registered assets, with the results reported on Form T1243 and, for larger holdings, Form T1161, and the exit rules are set out in our departure tax guide. Arriving works in reverse: your cost base for most property is reset to fair market value on the day you become a Canadian resident, and our moving to Canada from the US guide covers the arrival-year filings. In both directions, the Canadian and US returns share one set of dates, one set of exchange rates and one story about where you lived.

How we prepare a dual-status year

We build the move year as one file with two returns in it. We fix the residency start or end date first, test whether the first-year choice or the joint election improves the result, and then prepare the Form 1040 and Form 1040-NR with the correct one leading and the foreign tax credits matched to the Canadian T1 for the same period. Because the dates and the credits have to agree on both sides of the border, our US tax preparation and Canadian tax work are done by the same people.

Source: IRS — Taxation of dual-status individuals; IRS — Publication 519, US Tax Guide for Aliens.