Taiwan's 183-Day Rule: When Foreigners Become Tax Residents, and What Happens to Offshore Investments

You live in Taiwan: an engineer on a work permit, a teacher, or someone who moved here with a spouse. You keep a brokerage account back home or in the US, holding stocks and ETFs that pay dividends and generate realized gains. A question most people first ask in filing season: when does Taiwan start seeing your offshore investments?

The answer comes down almost entirely to one number: how many days you spend in Taiwan this year. At 183 days, your offshore investment income flips from completely outside Taiwan's tax net to inside Taiwan's alternative minimum tax. This article covers how the days are counted, exactly what changes when you cross the line, and three details foreigners routinely miss.

How the 183 days are counted

The legal basis is Article 7 of Taiwan's Income Tax Act. You are a Taiwan tax resident if either:

1. you have a domicile in Taiwan and habitually reside here (in practice this prong mainly applies to Taiwanese nationals with household registration), or
2. you have no domicile in Taiwan but stay in Taiwan for 183 days or more within one taxable year.

Foreigners generally have no Taiwan household registration and do not meet the domicile prong, so for you it is a pure day count. The tax authority's counting rules:

• The taxable year is the calendar year (January 1 to December 31). Days do not carry across years; the counter resets every January 1.
• Days are counted from passport entry and exit stamps (or the immigration agency's certificate of entry and exit dates).
• The arrival day does not count; the departure day does.
• Multiple entries and exits within the year are added together.

The tax bureau's own example: enter April 2, leave May 10 (38 days); re-enter July 2 and stay through year-end (182 days). Total for the year: 220 days. Resident.

There are actually three thresholds, not one

The 90-day line is about salary (the offshore-employer portion). The 183-day line is about your investments. This article is about the second one.

What flips at 183 days: a four-step legal chain

1. Taiwan's individual income tax is territorial: it taxes Taiwan-source income. Your US dividends and offshore capital gains are not Taiwan-source and never enter the regular income tax, whatever your status.
2. Residents, however, are also subject to the Income Basic Tax (Taiwan's alternative minimum tax, the AMT): overseas income counts toward the "basic income amount".
3. Non-residents are expressly excluded from the entire AMT regime (Income Basic Tax Act, Article 3, Paragraph 1, Subparagraph 5). Below 183 days, the AMT simply does not apply to you: Taiwan has no claim on your offshore investment income.
4. At 183 days you become a resident, the exclusion falls away, and your overseas income enters the basic income amount. The test is residence, not nationality: a foreigner at 183 days is treated exactly like a Taiwanese resident.

The mechanics once you are inside the AMT (each line has its own common misconception; the Chinese edition has a full myth-busting piece (in Chinese)):

• NT$1,000,000 is a cliff, not a floor: if the household's total overseas income for the year is below NT$1M, none of it counts; at NT$1M or more, all of it counts.
• The NT$7.5M deduction applies to the basic income amount (your regular net taxable income plus overseas income plus certain other items), not to overseas income alone. Basic tax = (basic income amount − NT$7.5M) × 20%.
• Then you compare: you only pay the excess of the basic tax over your regular income tax. Expats on high Taiwan salaries already pay substantial regular tax, which creates a large invisible buffer; the top-up is very often zero.
• Foreign tax paid is creditable, capped at the incremental basic tax attributable to that overseas income, and the law requires evidence of tax paid issued by the source-country tax authority (for US withholding, brokers' Form 1042-S is commonly accepted in practice, though the tax bureau may request further documentation).
• A zero top-up does not mean no filing: once the basic income amount exceeds NT$7.5M, you must file the basic tax return even if the amount payable is zero.

Three details foreigners routinely miss

Detail one: the planning unit is the year, not the arrival date

Resident status attaches to the whole taxable year: in a year where you stay fewer than 183 days you are a non-resident for that entire year, and offshore gains realized in that year are outside Taiwan's reach; in the year you cross 183 days, that year is a resident year. So the timing unit for realizing large gains is the year. If you will be living in Taiwan long-term from next year, and you want a large realization to stay outside Taiwan's net, complete it this year, not in the days before next year's arrival flight.

Detail two: dual residents should read the treaty first

Crossing 183 days in Taiwan does not switch off your home country's residence rules; you may be a dual resident. Taiwan has 35 income tax treaties in force (Japan, the UK, Australia, and others; the United States is not among them). Treaty tie-breakers (permanent home, center of vital interests, habitual abode, nationality) decide which side steps back. If your home country has a treaty with Taiwan, read it before computing any Taiwan tax. If it does not (including the US), both sides tax under their own rules and relief comes only from each side's domestic foreign tax credit.

Detail three: estate tax runs on completely different logic

Income tax asks how long you stayed. Taiwan's estate tax asks about nationality plus habitual residence: under Article 1 of the Estate and Gift Tax Act, a non-national is subject to Taiwan estate tax only on Taiwan-situs assets, no matter how many years they lived in Taiwan, and most status-based deductions (spouse, children) are unavailable to non-nationals. Your offshore portfolio never enters Taiwan's estate tax. Before you celebrate: your US stocks face the US estate tax instead, where nonresident aliens get a USD 60,000 exemption, entirely regardless of your Taiwan status. See the USD 60,000 threshold article.

Self-check list

• Have you actually counted this year's days? (Passport stamps; arrival day excluded, departure day included; multiple trips add up.)
• Will you cross 183 this year, or only next year? Have you thought about which year your large realizations belong to?
• Does your home country have a tax treaty with Taiwan? If so, what does the tie-breaker say?
• From your first resident year: does household overseas income reach NT$1M? Does the basic income amount exceed NT$7.5M (filing obligation)?
• Are you keeping evidence of foreign tax paid (Form 1042-S and the like)?

Takeaways

1. For foreigners, Taiwan tax residency is almost purely mechanical: 183 days in a calendar year, arrival day excluded, departure day included, trips added up, counter reset every January 1.
2. The biggest change at 183 days is not your salary, it is your offshore investments: from entirely outside Taiwan's tax net (non-residents are expressly excluded from the AMT) to inside it.
3. The regime has three buffers: the NT$1M inclusion cliff, the NT$7.5M deduction, and the comparison against your regular tax. High earners often owe nothing extra, but the filing obligation and the amount payable are two different questions.
4. Plan by year; dual residents read the treaty first (the US has none with Taiwan); and estate tax follows nationality, a completely separate system on both the Taiwan side and the US side.