Know exactly when your days start counting.
On an F-1 or J-1 visa, your first years in the US are exempt-individual years, your days of presence simply don't count toward the substantial presence test. Tax Days tracks both the exempt window and the day count, so you know the precise year you switch from nonresident to resident alien.
What you're up against
Exempt years are limited, and people miscount them
F-1 students are exempt individuals for 5 calendar years; J-1 students and trainees are generally exempt for 2 of the prior 6 years. Any part of a calendar year counts as a full year, which is the detail most people get wrong.
The day your status changes, the count begins
Once your exempt years run out, every day of presence starts counting toward the substantial presence test. The 5-year clock can quietly expire mid-degree, making you a resident alien without you noticing.
Form 8843 is required even with zero income
Every exempt individual, and their dependents, must file Form 8843 for each year they claim exempt status. Skipping it can jeopardize the exempt-day exclusion you're relying on.
OPT and the H-1B transition reset the math
OPT is still F-1 time, but if your exempt years are used up, those days count. Switching to H-1B mid-year can trigger the substantial presence test and a dual-status return, a very different filing.
What Tax Days does for you
Tracks every day you're present in the US so your substantial presence count is always accurate when the exempt window closes.
Lets you mark exempt-individual calendar years (5 for F-1, 2-of-6 for J-1) so days in those years are excluded from the count.
Projects the calendar year your exempt status ends and the substantial presence test starts applying to you.
Runs the 31-day current-year plus 183-day weighted formula (current year + 1/3 prior + 1/6 second prior) once your days begin counting.
Flags the year an OPT or H-1B transition is likely to make you a resident alien or trigger a dual-status return.
Keeps a contemporaneous trip log you can use to support Form 8843 and your residency position.
Stays on your iPhone. No servers, no accounts, no logs. Optional iCloud sync.
The rules you actually need to track
The substantial presence test, explained
The 31-day and 183-day weighted formula that determines resident vs. nonresident alien status once your exempt years end.
Read the guide →Exempt individuals & exempt days
Why F-1 and J-1 days don't count at first, the 5-year F rule, the 2-of-6-year J rule, and how a partial year counts as a whole year.
Read the guide →Form 8843 for students & trainees
Who must file, what it claims, and why filing it every exempt year protects your day-exclusion position.
Read the guide →From OPT to H-1B: when days start counting
How the cap-gap, OPT, and an H-1B start date affect your exempt window and the substantial presence test.
Read the guide →Dual-status returns for the switch year
What happens the year you become a resident, part nonresident, part resident, and how the day count drives it.
Read the guide →Closer connection & treaty positions
When a closer connection or a tax-treaty article can keep you nonresident even after the test is met.
Read the guide →
Free guides and tools
- Calculator
Substantial presence test calculator
Enter your days and exempt years and see whether you pass the test for the current year.
- Guide
F-1 & J-1 residency guide
The full playbook, exempt years, Form 8843, OPT, and the move to resident alien status.
- Calculator
183-day calculator
Once your exempt years are done, project the date your presence days cross the 183 threshold.
- Guide
SPT vs. green card test
The two ways to become a US resident for tax, and which one applies while you're on a student visa.
Common questions
Do my days on an F-1 visa count toward the Substantial Presence Test?
Generally not at first. As a student you're usually an exempt individual for five calendar years, so those days don't count toward the SPT. The exemption has conditions and doesn't apply forever, so track when your window ends.
What is Form 8843 and do I need to file it?
Form 8843 is how exempt individuals report their status to the IRS, generally required for every year you exclude days as a student even if you earned nothing. Missing it can complicate your ability to exclude those days.
What happens after my five exempt years are up?
Your US days start counting toward the Substantial Presence Test like anyone else's. Many students on OPT or a first H-1B year become US tax residents mid-year without realizing it. That's the year to count days carefully.
Does becoming a US tax resident change what income I report?
Generally yes: nonresidents report US-source income, while residents report worldwide income. The transition year can be a dual-status year with special rules, so precise dates for arrival, departure, and status changes matter.
Track your exempt years before they run out
Tax Days tells you the exact year your days start counting, so the switch to resident alien is never a surprise. £19.99/year.
