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British Expats Buying US Property: ISA, SIPP, and Pension Tax Guide

British professionals moving to the US with ISAs and SIPPs built up over decades are often surprised to learn their carefully built tax-efficient savings are not recognized as such by the IRS. Understanding this before becoming a US tax resident allows for restructuring. Understanding it after is more expensive.

The ISA Problem for US Tax Residents

British nationals who move to the US face a tax problem most financial advisors do not warn them about: UK ISAs (Individual Savings Accounts) lose their UK tax-free status for UK residents who become US tax residents. From the IRS's perspective, an ISA is simply a foreign financial account. Interest, dividends, and gains within an ISA are fully taxable by the US as earned, with no equivalent of the UK's ISA tax shield. Additionally, an ISA held by a US tax resident must be reported on FBAR (FinCEN Form 114) if the balance exceeds $10,000 at any point.

Consult both a UK tax adviser and a US CPA before moving to the US with an ISA.

SIPPs and US Tax: The PFIC Risk

SIPPs (Self-Invested Personal Pensions) are more complex than ISAs for US tax purposes. The IRS does not automatically recognize UK pensions as tax-deferred retirement accounts in the same way it treats 401(k)s or IRAs. The US-UK tax treaty (Article 17) provides some pension treaty protections, but the treatment of SIPP growth and distributions for US residents is an area of significant complexity and ongoing IRS guidance. Key risks: (1) SIPP distributions may be taxable in the US when received. (2) SIPP contributions may not reduce US taxable income. (3) SIPP investments in non-US mutual funds may be treated as PFICs (Passive Foreign Investment Companies) subject to punitive US tax treatment.

US Property and UK Pension Coordination

For British expats managing ISA and SIPP complexity while buying US property: the US property adds another layer of reporting (FBAR if foreign accounts are relevant, Form 1040 or 1040NR depending on residency). The key principle: buy US property in a structure that is clean from both US and UK perspectives. A US LLC owned by a British expat who is a US tax resident is straightforward for the US; the LLC structure may need to be considered from a UK angle for any future UK return. See: UK Citizens Selling US Property Guide and GBP/USD Currency Strategy.

What to Do Before Becoming a US Tax Resident

British nationals planning to buy US property and become US tax residents should: (1) Review ISA and SIPP holdings with a US-UK cross-border tax specialist before the move. (2) Consider restructuring UK fund investments to avoid PFIC designation. (3) Understand the US worldwide income reporting obligation that begins on the first day of US tax residency. (4) Ensure the US property ownership structure is clean from both US and UK tax perspectives.

Frequently Asked Questions

Does a UK ISA retain its tax-free status when the owner moves to the US?

No. From the IRS's perspective, an ISA is a foreign financial account. Interest, dividends, and gains within an ISA are fully taxable by the US for US tax residents.

Are UK SIPP distributions taxable in the United States?

Potentially yes, with some treaty protection under Article 17 of the US-UK treaty. The treatment is complex and depends on the type of SIPP and how distributions are structured. Consult a US-UK cross-border tax specialist.

What is a PFIC and why does it matter for British expats with SIPPs?

A PFIC (Passive Foreign Investment Company) is an IRS designation for certain foreign investment vehicles. UK unit trusts and non-US mutual funds held in a SIPP may be PFICs. PFIC treatment results in punitive tax rates on gains and interest charges. Restructuring before US tax residency begins is the solution.