US day calculator for snowbirds

Checked for the 2026 tax year · Updated October 2026

Free calculator: enter your days in the US for three years and see your IRS day count and whether you need Form 8840.

Not sure of your days? See how to count your US days. This calculator only does the day math; other things matter too, like US income or a green card application. The free check covers those.

How the IRS counts

The IRS adds every day you were in the US this year, plus one third of last year's days, plus one sixth of the year before. If you were in the US at least 31 days this year and the total reaches 183, you meet what the IRS calls the substantial presence test. Form 8840 lets you show that Canada is still your home, so you aren't taxed as a US resident.

More detail in Do I need Form 8840?

Onward is an independent Canadian service, not the IRS. This page explains the rules in plain terms; it isn't tax or legal advice. If your situation is unusual, speak with a cross-border tax professional.