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The short answer
Under the IRS substantial presence test you are a US tax resident for a calendar year if you were physically in the US for at least 31 days that year and at least 183 days over three years, counting every day this year, one-third of last year's days and one-sixth of the year before (IRS Publication 519, 2025). Days as an exempt individual, such as an F-1 or J-1 student in your first five calendar years, do not count.
Many Nigerians arrive in the US on a work visa, a student visa or as a dependant and assume their tax status follows their immigration status. It does not. For income tax, a non-citizen is either a resident alien or a nonresident alien, and unless you hold a green card, the answer comes from a day-counting rule called the substantial presence test. Getting it right decides which return you file, whether your Nigerian income is reported in the US, and which deductions you can use.
The two parts of the test
IRS Publication 519 (the 2025 edition, used for 2025 returns) sets out two conditions. You meet the test for a year only if both are true:
- You were physically present in the US on at least 31 days during the current year.
- Your weighted total over three years is at least 183 days: all the days you were present in the current year, plus one-third of the days in the year before, plus one-sixth of the days in the year before that.
Any part of a day counts as a day of presence unless one of the exclusions below applies. The test works on calendar years, January to December, not on the date your visa was issued.
Worked example
Example only. Chidi, a software engineer on an H-1B visa, spent 120 days in the US in 2025, 150 days in 2024 and 90 days in 2023. Neither visit made him an exempt individual.
| Year | Days present | Multiplier | Days counted |
|---|---|---|---|
| 2025 | 120 | All | 120 |
| 2024 | 150 | One-third | 50 |
| 2023 | 90 | One-sixth | 15 |
| Total | 185 |
He has more than 31 days in 2025 and 185 weighted days, so he meets the test for 2025. Had he spent 110 days in 2025, the total would be 175 and he would not.
Days that do not count
Publication 519 lists days you leave out of the count. The ones that most often matter for Nigerians are:
- Days in transit for less than 24 hours between two places outside the US, for example a connection through a US airport on the way from Lagos to Toronto.
- Days you could not leave because of a medical condition that arose while you were in the US (you must file Form 8843 to claim this).
- Days as an exempt individual, which covers most students, teachers and trainees in their early years.
- Days commuting regularly from Canada or Mexico, days as a crew member of a foreign vessel, and certain NATO visa days.
Students, teachers and trainees: the exempt-individual rules
If you are in the US on an F, J, M or Q visa as a student, your days are generally not counted for the first five calendar years. Publication 519 says you stop being exempt if you have been exempt as a teacher, trainee or student for any part of more than five calendar years, unless you can show you do not intend to live in the US permanently and have substantially complied with your visa.
Note the words "any part". A student who lands in August 2022 has used up 2022 as one full calendar year. Counting 2022, 2023, 2024, 2025 and 2026, that student's days begin to count from 2027 if they are still in the US on a student visa.
Teachers and trainees on J or Q visas have a tighter rule. They are not exempt for the year if they were exempt as a teacher, trainee or student for any part of two of the six preceding calendar years, with a narrow exception where a foreign employer paid all of their compensation.
When you pass the test but still are not resident
The closer connection exception can keep you nonresident even after you meet the test. Publication 519 says it applies only if you were present on fewer than 183 days in the current year, kept a tax home in a foreign country for the whole year, and had a closer connection to that country than to the US. You claim it on Form 8840. It is not available if you applied for a green card, took other steps towards permanent residence, or had an adjustment-of-status application pending during the year. For most Nigerians on H-1B or L-1 visas who are working towards a green card, that last condition rules it out.
When residency starts and what changes
The IRS page on residency dates (updated March 2026) says that if you meet the substantial presence test, your residency usually starts on the first day you were present in the US that calendar year, not on 1 January. If you also meet the green card test, the earlier date applies. That is why the year you arrive is often a dual-status year, explained in our guide to the dual-status tax year.
Once you are a resident alien, you are taxed like a US citizen on worldwide income. Salary from a Nigerian employer, rent from a flat in Lekki and interest on a Nigerian fixed deposit all go on the US return; whether relief is available for Nigerian tax already paid is a separate question for a preparer. Our explainer on how Nigeria taxes income you earn in the US covers the other side.
What to check first
- Get your actual travel dates. Use passport stamps, boarding passes and your own travel log, and keep them with your tax papers.
- Count days per calendar year, not per trip.
- Remove exempt-individual days and file Form 8843 for them.
- Apply the weighting and check both the 31-day and 183-day conditions.
- If you are close to the line, read Publication 519 in full or see a qualified preparer. This is information, not tax advice.
Where Pryme fits
Your tax status does not change how a Pryme account works, but it does change what you report. A Pryme account holds naira, dollars, pounds and euros in one place, so interest and transfers sit in one statement you can hand to a preparer. You can generate a verifiable statement through our partnership with VerifyDoc.ai (receipts and statements) and see how the account is set up on multicurrency accounts.
Questions people ask
How many days can a Nigerian stay in the US without becoming a tax resident?
There is no single number. You become resident under the substantial presence test if you have at least 31 days this year and 183 weighted days over three years (all of this year, one-third of last year, one-sixth of the year before). Someone who spends about 121 days every year will reach 181 to 182 weighted days and stay just under.
Does an F-1 student count days for the substantial presence test?
Generally not for the first five calendar years, because F-1 students are exempt individuals. Any part of a year counts as a year, and you still file Form 8843 to exclude the days.
Does a B1/B2 visitor visa protect me from US tax residency?
No. Visitor days count in full. Long and repeated visits to family can push you over 183 weighted days.
Does becoming a US tax resident mean I lose Nigerian tax residency?
Not automatically. The two countries apply their own rules. Check Nigeria's rules separately and check whether any treaty applies before assuming one replaces the other.
Sources
- IRS Publication 519 (2025), U.S. Tax Guide for Aliens · accessed Oct 2026
- IRS: Residency starting and ending dates (updated 14 Mar 2026) · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.