Every year, families from Hong Kong, Taiwan, Japan and Singapore relocate to the United States — for green cards, for children’s education, for business. Most discover the US tax system only after arriving. By then, the most valuable planning of the entire move has quietly expired.

The principle is simple: the day you become a US tax resident, the US acquires the right to tax your worldwide income — including gains that accrued long before you arrived. Everything in pre-immigration planning flows from managing that day and what crosses it with you.

First: when does US tax residency begin?

US immigration status and US tax residency are different clocks. Tax residency typically starts on your first day of presence as a green card holder, or earlier through the substantial presence test — a weighted day-count that long pre-move visits can trip accidentally. Exploratory trips, school visits and early relocation of one spouse can all start the clock before the family “officially” moves.

Step one of any plan is fixing the expected residency start date — and keeping pre-move days under control.

Realise gains while they are still foreign

The US taxes gains when realised, measured from your original cost basis — there is no automatic step-up on arrival. A property bought in Hong Kong in 2005, a stock portfolio built in Taipei, a stake in a family company: sell any of them after becoming a US resident and the entire historical gain is US-taxable.

The classic pre-immigration move is therefore to realise appreciated gains before residency begins — sell and repurchase securities to reset basis, complete planned property sales, or trigger gains in jurisdictions (like Hong Kong and Singapore) that will not tax them anyway. Done before the start date, the gain falls outside the US system entirely; done a month late, it is fully inside.

The same logic runs in reverse for losses: assets sitting at a loss are often better sold after residency begins, when the loss can do US work.

Restructure companies before, not after

Owners of Hong Kong, Taiwanese, Japanese or Singaporean companies face the US controlled foreign corporation rules on arrival — annual Form 5471 reporting and potential personal taxation of the company’s undistributed profits.

Pre-move options are rich: distributing accumulated earnings while still a non-resident, reorganising group structures, or making a check-the-box election (Form 8832) effective before residency so the company enters the US system as a transparent entity with stepped-up attributes. Post-move options are mostly damage control. If there is a company anywhere in the family, it belongs at the centre of the plan.

Trusts and family wealth: act while “foreign” still means foreign

Asian family structures — trusts in Hong Kong or Singapore, BVI holding companies, insurance wrappers — interact badly with US residency if left untouched:

  • A trust funded by someone who becomes a US person within five years of funding can be treated as a grantor trust of that person, pulling its income onto their US return.
  • US-person beneficiaries of foreign trusts inherit the Form 3520 reporting world and the punitive throwback rules on accumulated distributions.
  • Large gifts are dramatically simpler made before the recipient or donor becomes a US person.

Families with existing structures should have them reviewed — and where appropriate, distributed, domesticated or restructured — before anyone in the structure moves.

Smaller items that punch above their weight

  • Insurance products: investment-linked policies common in Hong Kong and Singapore often hold PFICs; review or replace before the move.
  • Local funds: swap into US-listed equivalents pre-move to avoid PFIC treatment; the swap itself is usually tax-free where you are now.
  • Retirement schemes (MPF, CPF and similar): generally not US-recognised; understand the reporting before arrival rather than after.
  • Spouse sequencing: when only one spouse needs US status, keeping assets with the non-US spouse preserves enormous flexibility.
  • Estate exposure: non-citizens domiciled in the US face US estate tax with a far smaller shelter than citizens enjoy; the move itself changes your estate plan.

The timeline that works

  • 12–6 months out: map assets, fix the expected residency date, review any company or trust, model the move.
  • 6–1 months out: execute — realise gains, restructure entities, complete gifts, replace problem investments.
  • Year one: first US return (often dual-status), FBAR and information reporting begin, and the plan is documented in the filings.

Pre-immigration planning has an unusual property for tax work: it is almost entirely legitimate, uncontroversial and explicitly contemplated by the rules — but only if it happens on time. The window closes precisely once.