International tax planning stopped being exotic the day work went remote and customers went global: a UK company with a developer in Spain, a founder relocating to Dubai, a US subsidiary and a SaaS customer base across forty countries now faces questions that used to belong to multinationals. The good news is that the rules, though intricate, are mostly mechanical — residence, permanent establishment, treaties, withholding — and the expensive failures are almost all failures of sequencing: structures discovered rather than designed. Here is the current UK landscape, for businesses and the individuals who own them.
Individuals: the FIG era
The old non-dom system is gone. Since April 2025, new arrivals who were non-UK resident for the previous ten years get the foreign income and gains (FIG) regime: four years of UK residence with qualifying foreign income and gains exempt — claimed annually, category by category, at the price of the personal allowance and CGT exemption, with foreign employment earnings running through their own overseas workday relief rather than a blanket pass. After year four, worldwide taxation — full stop, whatever your domicile. Everything therefore hangs on residence, which is why the statutory residence test now decides more tax than any other single set of rules for mobile individuals.
Two clocks are ticking for former remittance-basis users. The temporary repatriation facility lets former remittance-basis users designate pre-2025 foreign income and gains at a flat 12% — after which the designated funds can be brought onshore whenever convenient — but the current tax year is the last 12% year; 2027/28 designations cost 15%, and the facility closes entirely after April 2028. Anyone with meaningful offshore pots from the old regime should be running the designation decision this year, not next. And leavers planning the mirror-image move should remember the five-year temporary non-residence rule: gains realised during a short stint abroad come home to be taxed if you do.
Companies: residence and the accidental permanent establishment
A company is UK-resident if incorporated here — or, wherever incorporated, if its central management and control sits here. That second limb is the classic offshore-structure failure: the Dubai company whose board decisions are actually taken in a London kitchen is a UK company with paperwork abroad.
The live version of this risk now runs in both directions through remote work. An employee working habitually from a home office abroad can create a permanent establishment for a UK company — a fixed place of business, or a dependent agent habitually playing the lead role in concluding contracts — dragging a slice of profits into local corporate tax and filing obligations. Salespeople abroad are the highest-risk category; a policy on what remote staff may and may not do contractually is cheap insurance. The employer obligations travel too: PAYE continues by default (with a formal process to limit it to UK duties for treaty-split employees), and social security follows its own map — A1 certificates keep UK NIC running for staff posted to the EU, while the 52-week rule covers much of the rest of the world. Every long-term "working from Portugal" arrangement needs all three layers checked — corporate PE, payroll, social security — not just the one that came up in the HR conversation.
Cross-border structures: the current rulebook
For groups, the load-bearing rules in 2026: transfer pricing requires arm's-length terms on intra-group transactions, with the UK's SME exemption surviving the recent reform round (the proposal to strip medium-sized companies of it was dropped, though a new international transactions schedule is slated for 2027 — the direction is more disclosure, not less). The old diverted profits tax has been replaced by a recast charge on unassessed transfer pricing profits at corporation tax plus six points, and the largest groups live under Pillar 2's global minimum tax. Withholding taxes on dividends, interest and royalties remain the friction wherever the source country levies them (the UK itself imposes none on ordinary company dividends), managed through treaty claims made in advance — late claims mean cash trapped in foreign refund processes for years.
Double tax relief ties it together: treaties allocate taxing rights via tie-breakers, and the UK relieves by credit — foreign tax offset against UK tax on the same income, never more. The planning discipline is unglamorous: know which treaty applies, claim the right rate at source, keep the certificates of residence current (our SRT guide covers obtaining them), and document where decisions are actually made.
What good planning looks like — and what it doesn't
Legitimate international planning in 2026 is structural hygiene: the right entity in the right country for real activity, treaties used as designed, reliefs claimed on time, and substance matching paperwork. What no longer works — and now fails expensively, under exchange-of-information regimes that hand HMRC foreign account data automatically — is geography as decoration: brass-plate companies, offshore boards that never meet, income routed through jurisdictions where nothing happens. The gap between the two is precisely where professional advice earns its fee, ideally before the subsidiary is incorporated, the employee relocates or the founder books the one-way flight.
Acumon's international tax team handles the corporate side — PE reviews, transfer pricing, treaty claims, inbound UK subsidiaries — with expat tax covering the individuals: FIG claims, TRF designations, residence planning and the returns that tie it together. If your business or your life now spans borders that your tax arrangements predate, the review is overdue by definition.