US Tax Residency Start and End Dates for Hong Kong Moves: Substantial Presence Test and Treaty Tie-Breaker

The Internal Revenue Service’s ongoing enforcement focus on high-net-worth individuals with offshore ties, coupled with the 2025 rollout of the Corporate Transparency Act’s beneficial ownership reporting requirements, has placed renewed scrutiny on the precise tax residency start and end dates for Americans relocating to Hong Kong. For a US citizen or Green Card holder who departs the United States for Hong Kong on 1 March 2025, the date their US tax residency ends is not simply the day they board the flight. The interplay between IRC § 7701(b)’s Substantial Presence Test (SPT) and the tie-breaker provisions of the US-China Tax Treaty (applicable to Hong Kong via the US-HK Tax Information Exchange Agreement) can create a period of dual residency, during which the individual remains a US tax resident for a portion of the departure year even while physically present in Hong Kong. This article provides a technical roadmap for determining the start and end dates of US tax residency for a Hong Kong move, with precise statutory references, form filing obligations, and the 2025 treaty landscape.

The Substantial Presence Test: Counting Days Before and After the Move

The starting point for any US tax residency determination is the Substantial Presence Test codified in IRC § 7701(b). An individual is treated as a US resident for a calendar year if they are physically present in the United States on at least 31 days during the current year and 183 days during a three-year weighted period, calculated as: all days in the current year, plus one-third of days in the first preceding year, plus one-sixth of days in the second preceding year. For a Hong Kong-bound individual, the critical question is when the counting of US presence days stops and the counting of foreign days begins.

The 31-Day Minimum and the 183-Day Weighted Formula

The SPT is not a binary on/off switch. A US citizen who departs on 1 March 2025 and does not return to the United States for the remainder of the year will have zero US presence days from 2 March onward. However, the 183-day weighted formula for 2025 requires summing: (i) the 59 days present in the US from 1 January to 1 March 2025, plus (ii) one-third of days present in 2024, plus (iii) one-sixth of days present in 2023. If the individual had 120 days of US presence in 2024 and 180 days in 2023, the 2025 weighted total is 59 + (120 × 1/3 = 40) + (180 × 1/6 = 30) = 129 days. Since 129 is below 183, the individual fails the SPT for 2025 and is a nonresident alien for the full year, provided they do not meet the Green Card test. This result is counterintuitive: a US citizen who moves to Hong Kong in March can be a nonresident for the entire 2025 tax year if they had minimal US presence in prior years.

The Closer Connection Exception and Form 8840

For individuals who exceed the 183-day weighted threshold but are present in the US for fewer than 183 days in the current year, IRC § 7701(b)(3)(B) provides the closer connection exception. A taxpayer who is present in the US for fewer than 183 days in the current year can claim nonresident status if they maintain a tax home in a foreign country (e.g., Hong Kong) and establish a closer connection to that country than to the United States. The procedural vehicle is IRS Form 8840, Closer Connection Exception Statement for Aliens. The form requires the taxpayer to list the number of days of US presence in the current year and the two preceding years, the location of their tax home, and the foreign country to which they claim a closer connection. The filing deadline is the due date of the tax return (including extensions), typically 15 April 2026 for the 2025 tax year. A taxpayer who moves to Hong Kong in March 2025 and has 59 days of US presence in 2025 but 200 weighted days under the formula can still be a nonresident if they can demonstrate that their “tax home” is in Hong Kong for the remainder of the year and that their personal and economic ties are closer to Hong Kong.

The Treaty Tie-Breaker: US-China Tax Treaty Article 4 and Hong Kong

The US-China Tax Treaty, signed in 1984 and effective for US tax years beginning on or after 1 January 1987, applies to Hong Kong by virtue of the US-HK Tax Information Exchange Agreement (TIEA) and a separate exchange of letters confirming the treaty’s extension to Hong Kong. Article 4 of the US-China Treaty contains the standard tie-breaker rules for individuals who are residents of both contracting states under domestic law. For a US citizen living in Hong Kong, the treaty can override the SPT and deem the individual a Hong Kong resident for US tax purposes, but only if the individual is also a resident of Hong Kong under Hong Kong’s domestic law—which, under the Inland Revenue Ordinance (Cap. 112), is based on the territorial source principle and the concept of “ordinarily resident.”

The Permanent Home and Center of Vital Interests Tests

Article 4(2) of the US-China Treaty provides a cascading series of tests to determine which country has the closer economic and personal connection. The first test is the location of the individual’s permanent home. If the individual has a permanent home in both states (e.g., a condominium in New York and a flat in Hong Kong), the treaty looks to the “center of vital interests”—the state with which the individual’s personal and economic relations are closer. This is a facts-and-circumstances test. The IRS has historically considered factors such as the location of the individual’s family, the jurisdiction where the individual holds a driver’s license, the location of bank accounts and investment portfolios, and the country where the individual is registered to vote. For a Hong Kong move, the center of vital interests often shifts to Hong Kong if the individual sells their US home, moves their family, and establishes Hong Kong as their primary residence. However, the IRS’s position in Revenue Ruling 2019-23 is that a US citizen cannot unilaterally shed US tax residency by treaty unless they also surrender their US citizenship or Green Card, a position that has been challenged in Tax Court but remains the IRS’s stated view.

The Residency Starting Date Under the Treaty

For an individual who qualifies as a Hong Kong resident under the treaty tie-breaker, the US tax residency start date can be pushed to the date the individual establishes Hong Kong residency. Under Treasury Regulation § 301.7701(b)-4(c)(1), an individual who is a resident of a foreign country under a treaty can choose to treat the first day of the period of foreign residency as the first day the individual is a resident of the foreign country. This means that a US citizen who moves to Hong Kong on 1 March 2025 and qualifies as a Hong Kong resident under the treaty can treat their US residency as ending on 28 February 2025, even if they had US presence days in January and February. The individual must file Form 8833, Treaty-Based Return Position Disclosure, with their 2025 US tax return to claim this position. Failure to file Form 8833 can result in a penalty of USD 1,000 per failure under IRC § 6712.

Filing Obligations in the Year of Departure: The Dual-Status Return

A US citizen who moves to Hong Kong in the middle of the year may be required to file a dual-status return for the year of departure. A dual-status return is a single Form 1040 that reports income from two periods: the period during which the individual was a US resident (from 1 January to the date of departure) and the period during which the individual was a nonresident (from the date of departure to 31 December). The dual-status return is a complex filing because the US citizen must report worldwide income for the resident period but only US-source income for the nonresident period, subject to the sourcing rules of IRC §§ 861-865.

The Expatriation Rules for Long-Term Residents

For US citizens and Green Card holders who have been US residents for at least 8 of the last 15 years, the move to Hong Kong may trigger the expatriation rules under IRC § 877A. If the individual’s net worth exceeds USD 2 million on the date of expatriation or their average annual net income tax liability for the five preceding years exceeds USD 201,000 (2025 threshold, adjusted for inflation), they are a “covered expatriate” and subject to an exit tax on the unrealized gain of their worldwide assets. The exit tax applies to assets as if they were sold at fair market value on the day before expatriation, with an exclusion of USD 866,000 (2025 threshold, per IRC § 877A(a)(3)). For a Hong Kong move that is not accompanied by a formal renunciation of US citizenship, the expatriation rules do not apply unless the Green Card is formally surrendered. A US citizen who merely moves to Hong Kong remains a US citizen and is subject to worldwide taxation on their Hong Kong income, subject to the Foreign Earned Income Exclusion (FEIE) under IRC § 911.

Form 8938 and FBAR Compliance for Hong Kong Assets

A US citizen living in Hong Kong must file FinCEN Form 114 (FBAR) if the aggregate value of their foreign financial accounts exceeds USD 10,000 at any time during the calendar year. The FBAR filing deadline is 15 April 2026 for the 2025 calendar year, with an automatic extension to 15 October 2026. Separately, Form 8938, Statement of Specified Foreign Financial Assets, must be filed with the Form 1040 if the value of specified foreign assets exceeds USD 200,000 for a US citizen living abroad (or USD 400,000 for a married couple filing jointly). For a Hong Kong resident, this includes Hong Kong bank accounts, investment accounts, and interests in Hong Kong-incorporated companies. The penalty for failure to file FBAR can reach the greater of USD 100,000 or 50% of the account balance per violation under 31 U.S.C. § 5321(a)(5).

Actionable Takeaways

1. Determine your US presence days for the current year and two preceding years using the IRC § 7701(b) weighted formula before relying on any treaty tie-breaker, as the SPT is the default rule.
2. File Form 8840 by the 2025 tax return deadline (15 April 2026) if you are present in the US for fewer than 183 days in 2025 but exceed the 183-day weighted threshold, to claim the closer connection exception.
3. Attach Form 8833 to your 2025 Form 1040 if you are claiming treaty benefits under US-China Tax Treaty Article 4 to treat your US residency as ending on the date of your Hong Kong move.
4. File both FBAR (FinCEN Form 114) and Form 8938 for the 2025 calendar year if your Hong Kong financial accounts exceed the USD 10,000 and USD 200,000 thresholds, respectively.
5. Review the expatriation rules under IRC § 877A before any formal surrender of a Green Card, as the USD 2 million net worth threshold and the USD 866,000 exclusion amount are adjusted annually for inflation.

本文不構成稅務建議。涉及個人稅務情況請諮詢持牌會計師或稅務師。 / This does not constitute tax advice. Consult a licensed CPA or tax advisor for your specific situation.