Substantial presence test calculator: count your US days the way the IRS does

Pick the year you want to test. Then add each stay in the US with the day you arrived and the day you left; both are counted. Overlapping trips are merged, a stay over New Year is split between the two years, and days you mark as excluded are left out of the total. If you already know your totals, switch to typing them.

Nothing you type is sent anywhere. Trips are kept in this browser only, so they're still here when you come back; "Clear all trips" removes them.

IRS Publication 519 treats you as present on any day you are physically in the US at any time during that day.

There is no hour threshold. Land at 11.40 pm and that whole calendar day is in your count; take the first flight out at 6 am and that day is in too. "The United States" here means the 50 states, the District of Columbia and US territorial waters. It does not include Puerto Rico, Guam or the other US territories, and it does not include US airspace, so overflying the country costs nothing.

Six kinds of days you leave out

Everything else counts: holidays, family visits, medical treatment you came for, days you worked remotely for a foreign employer, days spent house hunting. Your I-94 travel history from US Customs and Border Protection lists your recorded arrivals and departures, which is a good starting point for the trip list above.

The weights make old days cheap and this year's days expensive. A day two years back is worth a sixth of a day; a day last year, a third. The receipts show how that plays out.

The third pattern catches frequent visitors: 121 days every year is the steady state that never trips the test, because 121 + 40.33 + 20.17 = 181.5. At 122 days a year the total reaches 183 from the third year on. Our rule of thumb for a regular visitor is to plan around 120 days a year and keep the receipts.

"Exempt individual" doesn't mean exempt from tax. It means the days don't count toward the test while you hold that status. There are four groups, each with its own time limit.

For diplomats, teachers, trainees and students, a spouse and unmarried children under 21 in the household whose visas depend on yours share the exemption. A business visitor on a B-1 or B-2 visa or under the Visa Waiver Program is not an exempt individual, which is the group most foreign company owners fall into. Mark exempt periods in the calculator with "Exempt individual days".

Meeting the test isn't always the end of the story. You can still be treated as a nonresident for the year if all three of these hold:

1. Fewer than 183 daysin the US in the year itself (actual days, not weighted).
2. A tax home abroadfor the whole year: your main place of business or work, or where you regularly live if you have none.
3. A closer connectionto that country than to the US, judged on your permanent home, family, belongings, affiliations, business, driving licence, voting and the residence you state on forms such as W-8BEN.

You claim it by attaching Form 8840 to your return, or by sending it alone if you don't have to file, by the Form 1040-NR due date: 15 June of the following year if you had no US wages with withholding, 15 April if you did. Miss it and the exception is lost unless you can show clear and convincing evidence that you tried to comply.

The substantial presence test doesn't override a tax treaty. If you are a resident of the US under the test and of another country under its own law, and the two have an income tax treaty with a residence tie-breaker, the treaty can decide that you are resident in the other country. You then figure your US tax as a nonresident, filing Form 1040-NR with Form 8833 attached, while still counting as a US resident for other purposes such as your residency dates.

Most US treaties follow the order in the OECD Model's residence article: where you have a permanent home, then where your personal and economic ties are closer, then where you habitually live, then nationality. Read the residence article of your own treaty from the IRS treaty list. Long-term green card holders should take advice first: Publication 519 warns that a tie-breaker claim can trigger the expatriation tax.

Residence under the test doesn't always cover the full calendar year. You can be a nonresident for part of a year and a resident for the rest, which the IRS calls a dual-status year.

Arriving

If you weren't a resident the year before, your residency starts on the first day you were in the US in the year you meet the test. Up to 10 days of earlier short visits can be left out of that date if you had a closer connection abroad on those days, though they still count toward the test itself. A signed statement goes with your return. The calculator above shows your first counted day for the year.

Leaving

In your last year, residence normally runs to 31 December. It can end earlier, on the last day you were in the US, if you keep a tax home abroad and a closer connection to it for the rest of the year and you aren't resident the next year. Up to 10 days of later visits can again be ignored for this date.

The first-year choice

If you don't meet the test this year but will next year, you can choose to be treated as resident from part of this year, provided you were in the US for 31 days in a row and for at least 75% of the days from the start of that run to 31 December, with up to 5 days away counted as present. People usually do it to file jointly or claim resident deductions.

"183 days" turns up in three different rules, and people mix them up. The US test is a weighted count over three calendar years. The UK test is a single tax year with its own way of counting days. And the treaty rule decides where an employee's salary is taxed, not where the person lives.

The UK statutory residence test, in brief

The UK tax year runs from 6 April to 5 April, and HMRC counts a day only if you are in the UK at midnight. The test runs in three steps, set out in HMRC's RDR3 guidance:

1. Step 1: automatic overseas testsNon-resident if any appliesFewer than 16 days in the UK if you were resident in one of the 3 previous tax years; fewer than 46 days if you were resident in none; or full-time work abroad with fewer than 91 UK days, of which fewer than 31 with more than 3 hours of work.
2. Step 2: automatic UK testsResident if any applies183 days or more in the UK; your only home in the UK for 91 days in a row, at least 30 of them in the tax year; or full-time work in the UK over a 365 day period.
3. Step 3: sufficient ties testDays and ties togetherFamily, accommodation, work and 90 day ties, plus a country tie if you were resident in any of the previous 3 years. The more ties, the fewer days it takes.

One catch: under HMRC's deeming rule, someone resident in one of the previous three years with at least three ties who is in the UK on more than 30 days without staying to midnight has every such day after the 30th counted anyway. Leaving at 11 pm every time doesn't work for long.

The 183 day rule in tax treaties

Most income tax treaties have an employment article built on Article 15 of the OECD Model Tax Convention. It lets an employee work in another treaty country and be taxed only at home if all three conditions hold:

• present there for no more than 183 days in any 12-month period starting or ending in the tax year (some older treaties use the calendar or fiscal year);
• paid by, or on behalf of, an employer that is not resident in that country;
• the pay is not borne by a permanent establishment the employer has there.

Publication 519 sets out the same three conditions for people working in the US, and notes that some treaties differ. Two things the rule is not: it is not a residence test, and it doesn't cover the self-employed or business profits, which most treaties handle under a separate article that looks for a fixed base or permanent establishment instead of a day count.

Plenty of people who own a US LLC from abroad never think about this test, because they rarely set foot in the US. The ones who should are the owners who go for conferences, meet clients, spend winters in Florida or move there in stages. Three things change.

None of this stops you running a US company from abroad, and an owner who visits a few weeks a year stays far from the line. It just means the calendar belongs in the same folder as the company papers.