US Tax Guide for Taiwanese Professionals

Tax Basics for Foreign Nationals

Working in the US on an H-1B visa makes you a US tax resident. That means:

• Worldwide income taxation — Not just your US salary. Taiwan savings interest, stock gains, rental income — all must be reported to the IRS.
• W-2 filing — Your employer provides a W-2 form each January showing annual income and taxes withheld.
• Filing deadline — April 15. Can extend to October 15 (but taxes owed must still be paid by April 15).

Your effective tax rate will be approximately 25-32% when you combine federal, state, and FICA. This is higher than Taiwan's top rate for most salary levels, but Arizona's flat 2.5% state tax is a significant advantage compared to other US states.

W-4 Filing and Withholding

When you start your job, you fill out a W-4 form that tells your employer how much federal tax to withhold from each paycheck. Getting this right matters:

• Too little withheld — You will owe a large amount at tax time and may face underpayment penalties.
• Too much withheld — You get a refund, but your cash flow was unnecessarily reduced all year.
• Filing status — If your spouse is in the US, "Married Filing Jointly" typically results in lower taxes. If your spouse is in Taiwan, the situation is more complex — ask your CPA.

Ask your HR department or CPA for help with the W-4 during your first week. Do not guess.

US-Taiwan Tax Treaty

The US and Taiwan do not have a comprehensive income tax treaty (unlike US-Japan or US-UK). This means:

• Your Taiwan income may be taxed in both the US and Taiwan simultaneously
• The US offers a Foreign Tax Credit to partially offset double taxation
• Taiwan has a similar mechanism — but you need your CPA to handle it
• This is an area where professional help is essential — do not guess

FBAR — Foreign Account Reporting

FBAR (Report of Foreign Bank and Financial Accounts) is the most easily overlooked filing obligation — and the one with the most severe penalties.

FATCA — Foreign Account Tax Compliance

FATCA (Foreign Account Tax Compliance Act) is similar to FBAR but separate:

You must file both if you exceed both thresholds. It is not either/or.

Key Deductions and Benefits

Understanding these can save you thousands of dollars:

• Mortgage interest deduction — If you buy a home, the interest on your mortgage (up to $750K loan) is tax-deductible. On a $400K loan at 7%, this is roughly $28,000 in deductions the first year.
• SALT cap ($10,000) — State and local tax deductions are capped at $10,000. This includes Arizona state income tax and property tax combined. Most semiconductor engineers hit this cap quickly.
• HSA (Health Savings Account) — If your employer offers a High Deductible Health Plan, you can contribute to an HSA — tax-deductible contributions, tax-free growth, tax-free withdrawals for medical expenses. Triple tax advantage.
• 401(k) contributions — Your employer likely offers a 401(k) retirement plan. Contributions reduce your taxable income. If your employer matches, contribute at least enough to get the full match — it is free money.
• Standard deduction — For 2026, the standard deduction is approximately $15,000 (single) or $30,000 (married filing jointly). You only need to itemize if your deductions exceed this.

Arizona State Taxes

• State income tax — 2.5% flat rate. This is a major advantage of Arizona. California tops out at 13.3%, New York at 10.9%.
• Property tax — Roughly 0.6% of assessed value. A $500K home is about $3,000/year. Much lower than Texas (1.6-1.8%) and New Jersey (2.2%).
• Sales tax (Transaction Privilege Tax) — Varies by city, typically 7-9%. Higher than Taiwan's 5% VAT. Note: Phoenix's sales tax rate differs from Scottsdale's.
• No estate tax — Arizona has no state estate tax (though federal estate tax still applies).

Tax Calendar

Finding a CPA

Do not attempt your first US tax filing alone. Find a CPA with foreign national tax experience:

Ask your semiconductor colleagues for CPA recommendations — many have already found good ones. CPA referrals are commonly shared in Taiwanese community LINE groups.

Common Mistakes

• Thinking Taiwan income does not need to be reported — The US taxes residents on worldwide income. Your Taiwan bank interest, stock gains, rental income — all of it must appear on your US tax return.
• Forgetting FBAR — Your Taiwan savings accounts, time deposits, brokerage accounts, and pension accounts — if the combined total exceeds $10,000 at any point, all must be reported.
• Using TurboTax alone the first year — Not recommended. Foreign national tax situations are too complex. After you understand the system, you can consider it for future years.
• Thinking an extension means extended payment — An extension to file is not an extension to pay. You must still estimate and pay your taxes by April 15.
• Not filing at all — Failure to file can have consequences beyond penalties. For visa holders, tax compliance issues can affect future immigration applications, including green card petitions.