Why this is difficult
The 183 figure is weighted across three calendar years, not a simple three-year sum. Some physical-presence days may be excluded, and meeting the arithmetic does not answer every exception or treaty issue.
Worked example
Fictional simplified arithmetic: 120 countable days in each of three years gives 120 + 40 + 20 = 180 weighted days. The 31-day current-year minimum is met, but the weighted total is below 183. This mirrors the IRS teaching example; personal exclusions still need review.
What to record or check
- Separate countable presence by calendar year.
- Confirm the current year has at least 31 countable days.
- Apply weights of 1, one-third, and one-sixth.
- Record possible transit, crew, medical, exempt-individual, or commuting exclusions for review.
Common mistakes
- Adding all three years at full weight.
- Ignoring the separate 31-day current-year minimum.
- Automatically excluding a day without checking IRS definitions.
- Treating the arithmetic as the end of a treaty or closer-connection analysis.
How StayCount helps
StayCount's US workspace separates current-year days, prior-year weighted rows, the 31-day minimum, and excluded spans. Its explanation shows how the entered facts contribute.
Official reference
IRS Substantial Presence Test guidance. Read the current official material for definitions, exclusions, and personal conditions.
Frequently asked questions
Are all days in the previous two years counted?
No. Countable days are weighted at one-third for the first preceding year and one-sixth for the second.
Is 183 days in the current year required?
No. The standard formula can reach 183 using weighted prior-year days, while also requiring at least 31 current-year days.
Does any part of a day count?
The IRS generally treats physical presence at any time during a day as a day, subject to listed exceptions.
What happens if the formula reaches 183?
Other exceptions, elections, treaties, and filing obligations may still matter. Seek qualified advice.
Important boundary
StayCount results depend on the facts you enter. StayCount is a planning tool, not immigration, legal, tax, or financial advice, and it does not guarantee an official outcome.