Mixed Fund Rules and the Remittance Basis Explained

For UK-resident non-domiciled individuals who used the remittance basis, the composition of their offshore accounts — what HMRC calls "mixed funds" — was arguably the most technically demanding aspect of their tax position. The mixed fund ordering rules determined precisely which income or gains were treated as remitted when funds were brought to the UK, and the consequences of getting this wrong were severe. Even now, following the abolition of the remittance basis from April 2025, the mixed fund legacy continues to affect those with historical offshore accumulations.

This guide explains how mixed funds arose, how the ordering rules worked, and what individuals with legacy mixed fund accounts need to consider today.

What Is a Mixed Fund?

A "mixed fund" arises when an offshore bank or investment account contains money from different sources — specifically, different categories of income, gains, or capital that are taxed differently under UK rules.

Under HMRC's framework, the relevant categories (in descending order of priority for taxation purposes) are:

1. Employment income relating to UK duties (taxable in the UK)
2. Other employment income (e.g., earnings for non-UK duties that have been subject to overseas tax)
3. UK income (other than employment income): rental income, dividends, interest from UK sources
4. Foreign income subject to UK tax (taxable as it arises on the arising basis)
5. Foreign income that arose while the remittance basis was claimed: income that was not taxed as it arose
6. Foreign chargeable gains (unremitted CGT)
7. Income and gains from pre-domicile periods (prior to becoming UK-resident)
8. Capital: money that was always clean capital — savings from pre-residence periods or funds that were never UK-taxable income or gains

The ordering matters because if money from category 1 or 2 (employment income) sits in an account alongside capital from category 8, any remittance is treated as coming from the most highly taxed category first. You cannot simply choose which category you are remitting.

How the Ordering Rules Worked

The mixed fund rules were introduced in 2008 and significantly extended in 2012. Under Section 809Q ITTOIA 2005 and the Income Tax Act 2007, where money in an account comprised funds of different types, remittances from that account were taxed according to a strict statutory ordering:

• The first money remitted was treated as the highest-ranked (most taxable) category in the account
• Working down through the categories, successive remittances drew on progressively less-taxable portions

This created two major problems:

Problem 1: Contamination. If employment income relating to UK workdays was paid into the same account as foreign investment income under the remittance basis, the entire account became "contaminated." Any remittance — even one intended to bring over clean capital — was treated as drawing on the UK employment income first.

Problem 2: Loss of flexibility. On the arising basis, you had no choice about when income arose (it was always taxable in the year of arising). Under the remittance basis, you deferred tax but then faced a complex web of ordering rules on eventual remittance. For individuals with large and long-standing offshore accounts, reconstructing the composition of those accounts to apply the ordering rules correctly was sometimes practically impossible.

Identifying the Contents of a Mixed Fund

The starting point for managing a mixed fund was to identify the composition of each offshore account — in effect, to produce a running record of:

• When each type of income or gain entered the account
• How much of each category was present at any given date
• What was remitted to the UK and when

This required keeping records stretching back potentially to 2008 (when the mixed fund rules first applied) or even earlier for some categories. For individuals who had held offshore accounts for decades and maintained the remittance basis throughout, this was an enormous record-keeping challenge.

HMRC accepted that in many cases precise records were not available. However, this was not a licence to ignore the rules — where records were inadequate, the taxpayer faced the risk that HMRC would apply the ordering rules in the most unfavourable way.

Strategies Used to Manage Mixed Fund Accounts

Sophisticated non-dom advisers used a range of strategies to manage mixed fund issues:

Segregated accounts. The most effective approach was to maintain separate offshore accounts for different categories of money. By keeping, say, employment income in one account and remittance-basis foreign income in another, and remitting only from the clean capital account, it was possible to control the tax profile of remittances. This required discipline, planning, and often multiple bank accounts.

"Cleansing" transfers. In 2017–18, HMRC introduced a temporary facility allowing individuals to reorganise mixed fund accounts by designating specific transfers to new accounts. This "cleansing" window closed on 5 April 2019. Those who used it successfully separated remittance-basis income from clean capital, significantly simplifying their future remittance position.

Targeted remittances. For accounts that could not be segregated, advisers sometimes planned remittances to deliberately draw down the most highly taxed layers first — accepting the immediate tax cost in exchange for a "cleaner" account thereafter.

Offshore investment bonds. Because insurance bond wrappers are not treated as "accounts" in the same way for remittance basis purposes, some non-doms used offshore bonds to accumulate investment returns without the mixed fund rules applying. Distributions from a bond were not generally treated as remittances of income or gains in the same way. This planning has its own complexities and is not without risk, but it was widely used.

The Post-2025 Legacy

From April 2025, the remittance basis was abolished for new arrivals (replaced by the FIG regime) and the Temporary Repatriation Facility (TRF) was introduced for those with historical remittance-basis income and gains. The TRF allowed those funds to be remitted to the UK at a flat rate of 12% (in 2025–26 and 2026–27) or 15% (in 2027–28) rather than at the full income tax or CGT rate.

For those with large historical mixed fund accounts, the TRF presented an opportunity to remit the accumulated pool of unremitted foreign income and gains at a significantly reduced rate. The normal mixed fund ordering rules were suspended for TRF remittances — you could designate which category of funds you intended to remit under the TRF, giving a degree of flexibility that did not exist under the standard remittance basis rules.

However, the TRF opportunity closes after 2027–28. After that, any remittances from historical mixed fund accounts revert to the standard rules — assuming you are back in UK residence and the accounts still contain unremitted foreign income or gains.

What to Do with a Legacy Mixed Fund Account

If you have historical mixed fund accounts that were built up under the remittance basis, the key steps are:

1. Reconstruct the composition. Work with a specialist UK tax adviser to reconstruct, as accurately as possible, the categories of income and gains in your offshore accounts. Even approximate records are better than none, and HMRC will expect reasonable effort to have been made.

2. Assess the TRF opportunity. If you did not use the TRF in 2025–26 or 2026–27, seek urgent advice — the 2027–28 year is the last opportunity to remit at the reduced rate. Weigh the cost of the TRF against the likely tax on eventual remittance under standard rules.

3. Consider whether to remit at all. If you are genuinely non-resident and do not intend to return to the UK, you may never remit the funds to the UK. In that case, the accumulated pool remains tax-deferred indefinitely (unless the IHT implications are a concern — see below).

4. Manage IHT. Since 6 April 2025, UK inheritance tax is residence-based rather than domicile-based: a "long-term UK resident" (broadly, UK-resident in at least 10 of the previous 20 tax years) is within the scope of UK IHT on worldwide assets. If the offshore funds fall within your IHT estate on this basis, the unremitted income and gains may be subject to UK IHT on death. This is now true regardless of whether they were ever remitted. Estate planning around these funds — potentially via trusts or other vehicles — should be reviewed.

5. Maintain records. Even if you have no immediate plans to remit, continue to maintain records of the composition of your offshore accounts. A future change of plans, return to the UK, or HMRC enquiry may make those records critical.

HMRC's Enforcement Stance

HMRC has historically treated remittance basis compliance — particularly mixed fund issues — as an area of significant non-compliance risk. The common failure is not deliberate evasion but rather the complexity of the rules and the difficulty of maintaining adequate records over many years.

HMRC's approach in enquiries into mixed fund positions has been to apply the ordering rules in the most unfavourable way where records are insufficient. This can result in a significantly higher tax charge than would have applied had the composition been properly documented.

If you have a historic mixed fund position and have not managed it correctly, the Worldwide Disclosure Facility (WDF) is available for voluntary disclosure. Penalties for proactive disclosure are substantially lower than for disclosures made after HMRC opens an enquiry.

How Global Investments Can Help

Global Investments works with specialist UK tax advisers who have deep experience of remittance basis and mixed fund issues. Whether you need help reconstructing your offshore account history, assessing the TRF opportunity, managing an HMRC enquiry, or planning your estate around historical offshore funds, we can connect you with the right expertise.

Our wealth management team also helps clients restructure offshore accounts and investment portfolios to comply with current rules and minimise future complexity. Contact us for a confidential discussion.

This article is for general information only. Tax rules are complex, change frequently, and depend on individual circumstances. Nothing here constitutes personal tax advice. Always seek independent professional guidance tailored to your situation. Investments can fall as well as rise in value.