What counts as a day in Idaho for the 270-day rule?

Presence in Idaho for any part of a calendar day counts as a full day spent in the state, unless you can show the presence was for a temporary or transitory purpose.

Do you need a home in Idaho to be caught by the 270-day rule?

Yes. The 270-day test requires both a place of abode maintained in Idaho for the entire tax year and more than 270 days in the state. Domicile is the separate route to Idaho residency and does not depend on the day count.

Idaho's 270-Day Residency Rule

Q: How many days can you spend in Idaho without becoming a resident?

Up to 270 days in the tax year. If you also maintain a place of abode in Idaho for the entire year, spending more than 270 days (271 or more) makes you an Idaho resident, even if you are domiciled elsewhere. Exactly 270 days keeps you under the day test.

A home kept in Idaho all year plus more than 270 days in the state makes you an Idaho resident, even if your true home is elsewhere. Here is exactly how the count works.

Last verified: July 2026

In short: Idaho treats you as a resident if you both maintain a place of abode in Idaho for the entire tax year and spend more than 270 days in the state during that year. This applies even if you are domiciled in another state or country. Presence for any part of a calendar day counts as a day in Idaho, unless the presence was for a temporary or transitory purpose. Note the line is 270 days, not 183.

Threshold: More than 270 days (271+)
Also required: Home in Idaho all year
Counting window: Tax year (calendar year)
A day counts if: Any part of a day in Idaho
Applies even if: Domiciled elsewhere
Legal basis: Idaho Code §63-3013

The rule

Idaho has two separate ways to be a resident: by domicile (Idaho is your true, fixed, permanent home) or by the 270-day day-count test. The day-count route has two conditions that must both be met:

A place of abode in Idaho. You maintain a dwelling in Idaho for the entire tax year. It does not have to be owned, and you do not have to live in it full time.
More than 270 days. You are present in Idaho for more than 270 days during the tax year. Exactly 270 days keeps you under the day test.

Meet both and you are an Idaho resident, taxed by Idaho on your worldwide income, even if you are domiciled in another state or country. Domicile is the other route: if Idaho is your permanent home for the whole year, you are a resident regardless of the day count.

How to count it

Confirm you maintained a place of abode in Idaho for the entire tax year.
Count every calendar day on which you were present in Idaho for any part of the day.
Leave out days on which your presence was solely for a temporary or transitory purpose, if you can show it.
Add the days across the whole tax year. Days do not need to be consecutive.
If the total is more than 270 and the place-of-abode condition is met, you are an Idaho resident for that year.

Example. You are domiciled in Texas but keep a cabin in Idaho all year. Across the year you are physically in Idaho on 285 days, many of them just for part of the day.

Because any part of a day counts, all 285 days count. With a place of abode plus more than 270 days, you are an Idaho resident, taxed on your full income, despite being a Texas domiciliary.

Beyond the day count

The 270-day test is only the day-count route. Idaho can also tax you as a resident by domicile, which turns on where your true, fixed home is rather than a day count. There is a narrow relief for people domiciled in Idaho who spend long stretches abroad: broadly, being absent from Idaho for at least 445 days in a 15-month period can make you a nonresident or part-year resident, subject to strict presence limits after that. And the day-count test always needs the place of abode, so days alone, without an Idaho home kept for the year, do not trigger it.

Official source: Idaho Code §63-3013, explained on the Idaho State Tax Commission guidance on residency page.

AtlasDays tracks Idaho's 270-day residency rule automatically

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FAQ

How many days can you spend in Idaho without becoming a resident?

Up to 270 days in the tax year. If you also keep a home in Idaho for the whole year, spending more than 270 days (271 or more) makes you a resident, even if you are domiciled elsewhere. Exactly 270 days keeps you under the day test.

What counts as a day in Idaho?

Presence in Idaho for any part of a calendar day counts as a full day, unless you can show the presence was for a temporary or transitory purpose.

Do you need a home in Idaho to be caught by the rule?

For the 270-day test, yes. Without a place of abode kept for the tax year there is no day-count residency, though separate domicile rules can still make you an Idaho resident.