Introduction
Eighteen months after the most significant changes to the UK’s non-domicile regime in a generation, the first wave of disputes is beginning to reach the First-tier Tribunal.
These cases offer early insights into how HMRC is interpreting the transitional provisions and where taxpayers may find themselves unexpectedly caught out.
The April 2025 Overhaul
The non-dom reforms that took effect on 6 April 2025 fundamentally reshaped the landscape for internationally mobile individuals.
The remittance basis of taxation was abolished for new arrivals, replaced by a four-year foreign income exemption.
Long-term residents who had previously claimed non-dom status found themselves subject to the new residence-based regime, with various transitional reliefs available to soften the blow.
The changes were intended to simplify the system and align the UK more closely with international norms. Whether they have achieved that goal remains debatable.
What is clear is that the transitional provisions, designed to bridge the old and new systems, have proven to be a fertile source of confusion and dispute.
The Transitional Relief Trap
One of the most contentious issues emerging in early tribunal cases concerns the interaction between the Temporary Repatriation Facility (TRF) and pre-existing remittance basis claims.
The TRF was introduced to encourage former non-doms to bring offshore funds onshore at reduced rates during a three-year window ending in April 2028.
HMRC’s position in several cases appears to be that taxpayers who made certain elections under the old regime cannot access the TRF on the same funds.
The precise boundaries of this restriction remain unclear, and the absence of detailed guidance in HMRC’s published materials has led to inconsistent treatment across different compliance offices.
In one recent case awaiting publication, a taxpayer who had claimed remittance basis for ten years attempted to use the TRF to repatriate funds accumulated during that period.
HMRC argued that because the taxpayer had made a section 809B nomination in an earlier year, the character of those funds was altered in a way that excluded them from TRF treatment.
The tribunal’s decision is expected to provide much-needed clarity on this point.
The Exit Charge Controversy
Perhaps the most legally complex disputes concern the deemed disposal rules that apply when long-term non-doms departed the UK around the time of the regime change.
The legislation imposes exit charges on certain unrealised gains, but the interaction with double taxation agreements has proven problematic.
Several affected taxpayers have argued that the exit charge provisions violate the UK’s treaty obligations, particularly where the destination country has no capital gains tax or taxes such gains only on realisation.
HMRC has defended the charges on the basis that they represent crystallisation of a UK tax liability that arose during UK residence, rather than new taxation of post-departure gains.
The outcome of these cases may ultimately depend on whether tribunals accept HMRC’s characterisation of the exit charge as a timing mechanism rather than a substantive expansion of the UK’s taxing rights.
The OECD Model Tax Convention commentary offers limited guidance on this relatively novel form of charge.
The Overseas Workday Relief Hangover
A separate category of disputes has emerged around Overseas Workday Relief (OWR), which was retained in modified form after April 2025.
Under the new rules, OWR is available for the same four-year period as the foreign income exemption, but the mechanics of claiming it have changed.
HMRC has challenged several taxpayers who claimed OWR under the old rules in 2024/25 and attempted to continue claiming under the new rules from 2025/26 onwards.
The department’s argument is that the four-year clock for OWR purposes begins from the date of arrival in the UK, not from April 2025.
This interpretation means that some taxpayers who had been UK resident for several years before the reforms find themselves unable to access OWR at all under the new regime.
This interpretation has significant financial consequences for senior executives and other internationally mobile employees who structured their compensation on the assumption that OWR would remain available.
The first tribunal decision on this point is expected before the end of 2026.
Practical Implications for Advisers
The emerging case law suggests several areas where practitioners should exercise particular caution:
- Review clients’ historic elections and nominations carefully before assuming TRF availability
- Consider treaty protection arguments early where exit charges apply
- Document the basis for OWR claims thoroughly, particularly regarding arrival dates and the four-year computation
- Maintain contemporaneous records of the reasoning behind transitional elections, as HMRC is actively challenging elections it considers to have been made without proper consideration
What Comes Next
The non-dom transition disputes are likely to intensify over the next twelve months.
The TRF window closes in April 2028, creating urgency for taxpayers who wish to repatriate funds but face uncertainty about their eligibility. HMRC has indicated it will prioritise these cases given the time-limited nature of the relief.
The Upper Tribunal may see its first non-dom transition appeals by mid-2027, providing authoritative guidance on the most contentious interpretation questions.
Until then, practitioners and taxpayers alike must navigate a landscape where HMRC’s published position and its litigation stance do not always align.
For those caught in the transitional provisions, the cost of getting it wrong can be substantial. The difference between qualifying for TRF at 12% and being subject to full income tax rates on remittance could amount to hundreds of thousands of pounds on significant offshore holdings.
The stakes warrant careful analysis and, in appropriate cases, willingness to challenge HMRC’s more aggressive interpretations through the tribunal system.