Tax Guide for International Students and Workers: FICA, Treaties, and Filing 2026

FICA exemptions, treaty benefits, and 1040NR rules explained clearly for F-1, OPT, STEM OPT, and H-1B workers filing US taxes in 2026.

April arrives every year with the same mix of dread and confusion: W-2s, 1042-S forms, treaty exemption worksheets, and a growing suspicion that you are somehow filing the wrong return. If you are an international student on F-1 or OPT, or a professional on STEM OPT or H-1B, that suspicion is often correct — because the US tax system has a separate track for nonresident aliens, and most software products steer you straight past it.

This guide covers everything you need to get right for tax year 2025 (returns due April 15, 2026): which form you file, why you are likely exempt from FICA, how tax treaties can cut your withholding to zero, and the exact moment you cross from nonresident-alien to resident-alien status. It also covers what commonly goes wrong and what to fix before you file.

Resident alien vs. nonresident alien — the split that determines everything

Before FICA, before treaties, before any form selection, you need to answer one question: are you a resident alien or a nonresident alien for federal tax purposes? This is entirely separate from your immigration status.

The IRS uses two tests, in order:

1. Green card test — If you held a green card at any point during the year, you are a resident alien for the whole year (with limited exceptions).
2. Substantial Presence Test (SPT) — You are a resident alien if you were present in the US at least 31 days in the current year AND the weighted sum of days is 183 or more (current year days × 1 + prior year days × 1/3 + two-years-ago days × 1/6).

The F-1 / J-1 exemption from SPT: Days spent in the US as an F-1 or J-1 student (including OPT and STEM OPT periods) are exempt from the SPT count for the first five calendar years you hold F-1 or J-1 status. This means most students in years 1-5 of F-1 are nonresident aliens regardless of how many days they physically spent in the country.

Once you switch to H-1B, your days start counting toward the SPT immediately. Many people flip to resident-alien status partway through the first H-1B year. The year of transition requires a dual-status return — 1040-NR for the nonresident period and a dual-status statement for the resident period.

Quick reference: which form to file

Before doing anything else, pin down your classification. The wrong form is not a minor error — it changes your deductions, your credits, your rates, and your FICA obligation.

FICA exemption for F-1, OPT, and STEM OPT students

FICA stands for the Federal Insurance Contributions Act — the combined 6.2% Social Security tax and 1.45% Medicare tax that appear as separate line items on every US paycheck. For a worker earning $60,000 a year, that's roughly $4,590 automatically withheld, plus an equal employer match.

Nonresident alien F-1 and J-1 students are exempt from FICA. This exemption is codified at IRC §3121(b)(19) and applies to wages earned for services performed to carry out the purpose for which you were admitted — including work authorized under OPT and STEM OPT.

Conditions for the FICA exemption to apply:

1. You must be a nonresident alien (pass the SPT analysis above — typically years 1-5 of F-1)
2. You must be in lawful F-1, J-1, M-1, Q-1, or Q-2 status
3. The services must be allowed under your authorized status (on-campus employment, CPT, OPT, STEM OPT all qualify)

What this means practically: If your employer is withholding FICA and you believe you qualify for the exemption, you should notify your HR or payroll department and provide a copy of your visa documentation. Employers are required to stop withholding once they confirm the exemption applies. If FICA was withheld in error, you can request a refund from your employer first; if the employer refuses or has already remitted to the IRS, file Form 843 with a copy of your Form 8316 to claim the refund directly from the IRS.

The exemption ends when you become a resident alien. Once you flip from nonresident to resident alien status — typically sometime during H-1B year one — FICA withholding is required like any other US worker. Your employer is responsible for making this change, but confirm it happened.

Tax treaties — what they are and how to claim them

The US has income tax treaties with roughly 65 countries. These treaties often include a specific article covering students and trainees, and sometimes a wages article covering employment income more broadly. Treaties can:

• Exempt student stipends, fellowships, or scholarship income from US tax
• Exempt wages (for limited years) from US tax
• Reduce the withholding rate on investment income (dividends, royalties) from 30% to a lower rate

How to find your treaty

Visit IRS.gov and search "tax treaty tables." The IRS maintains Publication 901 (US Tax Treaties) and individual treaty texts. Your home country's treaty article on "Students and Apprentices" or "Wages" will spell out the conditions and limits.

Common treaty student exemptions (illustrative examples)

Always verify current treaty language at IRS.gov — treaty details change, and this guide's examples are general illustrations. Your specific situation may differ.

Claiming a treaty benefit on 1040-NR

On Form 1040-NR, you report the treaty-exempt income on the appropriate line, then subtract it with the treaty article cited. You must also complete Form 8833 (Treaty-Based Return Position Disclosure) if the treaty benefit reduces your tax liability and the relevant income exceeds $10,000 (or in some cases $100,000). Failing to attach Form 8833 when required can result in a $1,000 penalty per transaction.

The 1042-S form — what it means and what to do with it

If you received scholarship income, fellowship income, or payments subject to withholding as a nonresident alien, your school or employer will issue a Form 1042-S (Foreign Person's US Source Income Subject to Withholding) rather than a W-2 for that income.

Common situations producing a 1042-S:

• Tuition waivers for graduate students in excess of tuition/required fees (the "excess fellowship" portion is taxable income)
• Wages paid to nonresident aliens where a treaty exemption was claimed — the employer still reports it on 1042-S even if zero was withheld
• Prizes, awards, royalties paid to nonresident aliens

You will report the income on your 1040-NR in the appropriate section. If withholding was taken and you are due a refund (for example, 30% was withheld but a treaty reduces your rate to 0%), the 1040-NR is how you recover it.

Step-by-step filing timeline for 2025 returns

Use this sequence to stay organized:

1. By January 31: Gather W-2s from all employers. Note whether FICA was withheld — if it was and you believe you were exempt, flag this.
2. By February 15: Receive Form 1042-S from your university or any fellowship payer.
3. By March 1: Determine your tax classification (nonresident vs. resident alien, per SPT analysis above).
4. By March 15: Check your home country's tax treaty. If a student or wages article applies, pull the treaty text and the relevant article number.
5. By April 1: Use a nonresident alien-specific tax filing tool (GLACIER Tax Prep, Sprintax, or a CPA familiar with 1040-NR). Do NOT use TurboTax or H&R Block for a 1040-NR — these tools file 1040 returns and will misclassify you.
6. April 15: File 1040-NR (or Form 8843 if no US income) by this date. Extensions are available (Form 4868) but extend the filing deadline, not any payment due.
7. If you owe FICA refund: File Form 843 separately; this is independent of your annual income tax return.

State taxes

Filing a federal return does not discharge your state tax obligation. Most states follow federal classification rules for residency, but some have their own tests. California, New York, Massachusetts, and other high-income states have substantial state income taxes. Some states have their own treaty-like exemptions for students; most do not. Check your state's department of revenue website for nonresident filing requirements.

Note: if you earned income in multiple states (for example, an OPT job in New York and a summer internship in California), you may owe returns in both states. Your W-2 will show state withholding by state.

The transition year — when STEM OPT becomes H-1B

The year you convert from STEM OPT to H-1B is typically the most complicated tax year you will have. Here is what changes:

• FICA kicks in the moment your H-1B is effective (October 1 for standard cap-subject H-1B, earlier for cap-exempt employers). Your employer should start withholding FICA from that date.
• SPT starts accumulating from the date H-1B becomes effective.
• You likely file a dual-status return — 1040-NR for the period you were nonresident, plus a dual-status attachment for the period you became resident. The year of first H-1B is almost always a dual-status year unless H-1B started on January 1.
• Deductions become more favorable once you are a resident alien: you can claim the standard deduction, you can file jointly with a spouse (if applicable), and most refundable credits open up.

For the dual-status year, most people benefit from working with a CPA who has specific experience with nonresident-to-resident transitions. The rules for what income is included in each period can be complex, especially if you have overseas investment accounts or received foreign income.

Also worth reviewing as you build financial stability: building US credit history as an international and getting your SSN and driver's license are often parallel first-year tasks that interact with tax setup in HR systems.

What H-1B holders should know about ongoing tax filing

Once you are established on H-1B and filing as a resident alien, your federal return is largely similar to any other US worker's. A few H-1B-specific considerations:

• Foreign financial accounts: If you have non-US bank accounts with a combined balance exceeding $10,000 at any point during the year, you must file an FBAR (FinCEN Form 114) by April 15 (with automatic extension to October 15). This is separate from your tax return. Penalties for non-filing are severe.
• FATCA (Form 8938): If foreign financial assets exceed certain thresholds ($50,000 for single filers, higher for married), attach Form 8938 to your 1040. This is a different form from the FBAR but covers similar territory.
• Home country taxes: Your home country may still claim you as a tax resident. India, China, South Korea, and other countries have their own residency rules. The US-India, US-China, and US-Korea tax treaties address double-taxation for most income types, but you may still need to file in your home country and claim a foreign tax credit.
• Stock compensation: RSUs and stock options are common in tech roles. For H-1B holders, the tax treatment of RSUs — ordinary income at vesting, reported on your W-2 — is the same as for US citizens. However, if your grant date was before you arrived in the US, there can be a sourcing issue (part of the RSU value may be foreign-source income). See our overview of equity and RSU considerations for visa holders for more on this.

Common mistakes

These are the errors that generate IRS notices, cost refunds, or create problems during visa renewals:

• Filing Form 1040 instead of 1040-NR when you are still a nonresident alien. TurboTax and most consumer software products only support the 1040. Using the wrong form misrepresents your residency status and can affect FICA refund eligibility.
• Skipping Form 8843 when you had no income. If you were in F-1 or J-1 status and had zero US income, you still must file Form 8843 to document your exempt days. Failing to file it can cause the IRS to later count those days in the SPT, which could retroactively change your status.
• Not claiming a treaty benefit you qualify for. Students from China, South Korea, India, and many other countries have treaty provisions that reduce or eliminate US tax on certain income. Missing these leaves money on the table every year.
• Allowing FICA withholding during OPT without requesting a refund. Employers sometimes withhold FICA from OPT workers in error. You have until three years after the original return due date to file Form 843 and reclaim that money.
• Failing to file FBAR. This is a separate FinCEN form, not part of your IRS tax return. Many international students with home-country bank accounts over $10,000 are unaware of the obligation. Penalties start at $10,000 per violation for non-willful failures.
• Mixing up gross income and tax treaties on the 1040-NR. You must report the full amount of income on the 1040-NR and then subtract the treaty-exempt portion on the treaty line — not simply omit the income. Omitting it entirely raises questions about underreporting.
• Ignoring state taxes. Some international students assume that because they are exempt from federal tax under a treaty, they are also exempt from state tax. State tax obligations are independent of federal; most states do not adopt federal treaty provisions.

Frequently asked questions

Do F-1 students have to pay FICA taxes?

Generally no. F-1 students who are nonresident aliens for tax purposes are exempt from FICA (Social Security and Medicare) taxes on wages earned while in authorized status. This exemption applies during F-1, OPT, and STEM OPT as long as you remain a nonresident alien under the Substantial Presence Test.

What form do international students file instead of the regular 1040?

Nonresident aliens file Form 1040-NR. It covers US-source income and is separate from the standard Form 1040 that US residents and citizens file. If you had no US income at all, you may still need to file Form 8843 to document your exempt status.

How do I know if a tax treaty reduces my US tax?

The IRS publishes a full list of US tax treaties by country at IRS.gov. Check if your home country has a treaty and read the student or wages article. If it applies, you claim the exemption or reduced rate using the appropriate treaty article number on your 1040-NR and attach a disclosure statement.

When do I switch from 1040-NR to 1040 as I transition to H-1B?

You switch once you pass the Substantial Presence Test — roughly 183 days of US presence in a calendar year, weighted across three years. Many people switch during their STEM OPT or H-1B year. You may also file a dual-status return the year you cross the threshold.

Can I claim the same deductions and credits as US citizens?

Not always. Nonresident aliens cannot claim the standard deduction (except for students from India under the India-US treaty), cannot file jointly with a spouse, and are ineligible for many refundable credits. Once you become a resident alien for tax purposes, most credits become available.

Resources worth bookmarking

• IRS Publication 519 (US Tax Guide for Aliens) — the authoritative source on resident vs. nonresident classification and all Form 1040-NR rules
• IRS Publication 901 (US Tax Treaties) — country-by-country treaty summaries
• GLACIER Tax Prep and Sprintax — the two main software products built specifically for 1040-NR filers
• FinCEN BSA E-Filing System — where you file the FBAR (separate from IRS.gov)

As you settle into your first US job, taxes are one of several financial systems that work differently than you expect. The first 90 days as an international hire covers the broader onboarding picture — benefits enrollment, 401(k) decisions, and payroll setup — all of which interact with your tax situation.

Questions about your specific tax situation as an international professional? F1Jobs works with candidates at every stage of the F-1-to-H-1B journey and can point you toward the right resources.