Year-End Tax Planning for Cross-Border Filers: Canada-US Checklist

Cross-border filers have year-end planning opportunities in both countries, and the deadlines do not always align. The US tax year ends December 31, and most elections (Roth conversions, capital loss harvesting, charitable donations, estimated tax payments) must be completed by then. Canada’s tax year also ends December 31, but the RRSP contribution deadline extends to March 1 of the following year, which creates a planning window that domestic filers in either country do not have. When you file in both countries, optimizing one return can change the foreign tax credit calculation on the other, so the two returns need to be planned together.

What are the December 31 deadlines?

Both the US and Canadian tax years end December 31. Actions that must be completed by that date include:

• Capital loss harvesting. Any sales intended to realize losses must settle by December 31. In the US, stock trades settle T+1 (one business day after the trade date), so the last trading day that settles in the current year is typically December 30. In Canada, the settlement date generally does not affect the tax year of the disposition (the trade date controls), but confirm with your broker.
• Roth IRA conversions. Converting a traditional IRA to a Roth IRA creates taxable income in the year of conversion. The conversion must be completed by December 31. For a US citizen in Canada, the Roth conversion increases US income (and potentially Canadian income, since Canada does not recognize the Roth’s tax-free status), which affects the FTC calculation.
• Charitable donations. Donations must be made by December 31 to qualify for the tax year. The charitable donations cross-border guide covers the treaty interaction (Article XXI(7)) and the source-country income limitation.
• Required Minimum Distributions (RMDs). US retirement account holders age 73+ must take their RMD by December 31 (except for the first RMD year, which can be deferred to April 1). Missing the RMD triggers a 25% excise tax on the amount that should have been withdrawn.
• US estimated tax. The Q4 estimated payment is due January 15, but paying by December 31 avoids the underpayment penalty for the calendar year.

What about the RRSP contribution deadline?

The RRSP contribution deadline is unique: contributions for a tax year can be made until 60 days after the end of the year (typically March 1, or February 29 in a leap year). This means you can assess your final income for the year in January, then make (or top up) your RRSP contribution before March 1 to reduce Canadian taxable income for the prior year.

• For a US citizen in Canada, the RRSP contribution also affects the US return. Under the treaty (Article XVIII(7)), a US citizen can elect to defer US tax on RRSP contributions and income, but the election must be made on the US return (by attaching a statement or filing Form 8891, now simplified). The RRSP contribution reduces Canadian tax (increasing the FTC limitation on the US return), which affects the overall tax position.
• For someone who moved to Canada during the year, the RRSP room may be limited (it is based on prior-year Canadian earned income), but any available room can be used before March 1.

How does loss harvesting work across the border?

Loss harvesting must satisfy both the US wash sale rule and the Canadian superficial loss rule. The 31-day waiting period (after the sale) applies in both countries, so any repurchase of the same or substantially identical security must wait until at least January 1 if the sale was on November 30 or earlier.

• The cross-border dimension: a loss that is allowed on one return may be denied on the other if the repurchase rules differ (for example, a spouse repurchase triggers the Canadian superficial loss rule but not the US wash sale rule). Model both returns before harvesting.
• For US citizens in Canada, the capital loss deduction asymmetry matters: the US allows $3,000 of net capital losses against ordinary income per year, while Canada allows capital losses only against capital gains. A loss that has immediate value on the US return may carry forward indefinitely on the Canadian return.

Should I accelerate or defer income?

The answer depends on the rate differential between the two countries and the FTC position:

• If the Canadian rate is higher than the US rate (the most common situation for employment income), accelerating income into a year when Canadian rates are high produces more FTC to use on the US return. This can be beneficial if you have excess FTC that would otherwise expire.
• If you are moving between countries in the coming year, the rates in each country may change dramatically. Accelerating income into the pre-move year (when you know the rates) can be better than deferring it into the post-move year (when the rates and residency are uncertain).
• RRSP contributions reduce Canadian income (and Canadian tax), which reduces the FTC available on the US return. This is generally still beneficial (the RRSP deferral is worth more than the FTC reduction), but the net benefit should be modeled.

What about estimated tax and instalments?

Both countries require estimated payments (US) or instalment payments (Canada) if the tax owing exceeds certain thresholds. Missing the deadlines triggers penalties in both countries.

US estimated tax: quarterly payments are due April 15, June 15, September 15, and January 15. For cross-border filers, the Q4 payment (due January 15) is the last opportunity to reduce the underpayment penalty for the prior year. Paying 100% of the prior year’s tax (110% if AGI exceeds $150,000) by the January 15 deadline avoids the penalty entirely.

• Canadian instalments: quarterly payments are due March 15, June 15, September 15, and December 15. The CRA calculates instalment interest on the difference between the required instalments and the actual payments. The December 15 payment is the last one for the tax year.
• The estimated tax and instalments guide covers the thresholds and safe harbor calculations for both countries.

What elections should I review before year-end?

Several elections must be made by the return filing deadline but should be planned before year-end because they depend on year-end actions:

• Section 6013(g) election (filing jointly with a non-resident spouse): must be made on a timely filed return. The decision to file jointly or separately affects the tax brackets, the FTC limitation, and eligibility for credits.
• Treaty-based return position (Form 8833): if you are taking a treaty position that differs from the default US treatment (tiebreaker residence, pension exemption, service income allocation), the disclosure is due with the return but should be planned before year-end.
• RRSP treaty election: the election to defer US tax on RRSP income is made on the US return but depends on whether the RRSP is a registered plan and the amount of the contribution.

What should I do next?

Before December 31, model both returns (US and Canadian) with your current income, deductions, and credits. Identify whether loss harvesting, Roth conversions, RRSP contributions, charitable donations, or income acceleration/deferral would reduce the combined tax position. Then execute the actions before the applicable deadline.

• Wash sale and superficial loss rules, the cross-border loss harvesting rules
• Estimated tax payments and instalments, the payment deadlines
• Charitable donations cross-border, the treaty interaction on donations
• Cross-border filing deadlines, the full calendar for both countries
• RRSP contributions as a US citizen, the treaty election
• Capital loss carryforward, using up losses before a move strands them
• FTC limitation and carryover, the limitation formula and strategies to avoid excess credits expiring

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