How UK SIPPs, workplace pensions, ISAs, and US retirement accounts are treated across both tax systems — and how the treaty helps.
ISAs are tax-free in the UK and almost always classified as PFICs (passive foreign investment companies) by the IRS. Without the right elections, a single year of ISA gains can be taxed at the highest US ordinary income rate plus an interest charge that compounds annually. UK pensions get a mostly favourable treaty treatment — but only if reported on the right form, with the right disclosure. The cost of getting this wrong tends to be invisible until you're filing the return three years late.
Each one is a separate service with its own page — click Learn more on any block below to see the full scope, deliverables, and pricing notes.
How SIPPs and workplace pensions are treated under US law and the US-UK treaty — contributions, growth, and distributions.
SIPP, workplace pension — US treatment.
Learn moreHow the UK taxes your US retirement accounts during growth, contributions, and distributions — and how the treaty interacts.
US retirement plans & UK reporting.
Learn moreISAs are not tax-free for US persons. Unit trusts, OEICs, and investment funds inside ISAs are typically PFICs.
ISAs reportable as PFICs.
Learn moreWe map every UK and US-side investment vehicle you hold — pensions, ISAs, GIAs, brokerage — and flag the ones that need US disclosure.
Identify which holdings are protected under the US-UK treaty (most pensions are) and which need PFIC, FBAR, or FATCA reporting.
Decide on QEF vs. mark-to-market elections for any PFICs, document the choice, and time it to your filing deadline.
Reconcile contributions, distributions, and rollovers each year — and watch for life events (career change, return to US, retirement) that change the math.
I'd held an ISA for eleven years thinking it was tax-free. The catch-up cost stung — but TaxStone got us into compliance under the streamlined programme and built a real plan for the rest of my life across both countries.
We can run a first-pass exposure read from these documents alone — no commitment to engage.
Send us a one-paragraph description of your situation and we'll tell you which filings are actually on the hook.
