Mixed Member Rules Explained: Key lessons from recent case law

We have previously discussed the Bluecrest Case, which mainly focussed on salaried members rules.  As we await the judgment from the Court of Appeal on that case, another partnership tax case HMRC v HFFX LLP; Atkins and others v HMRC has hit the headlines.  These two cases considered the ‘mixed member rules’ and in both instances HMRC’s argument that these rules applied was rejected.

The Supreme Court’s decision in the HFFX LLP case provides important clarification on the taxation of deferred remuneration and incentive arrangements within partnerships and LLPs. The Court unanimously held that amounts received by individual members under HFFX LLP’s incentive scheme were not “profit shares” for the purposes of Income Tax but still taxable as income under the miscellaneous income provisions.

What are the Mixed Member Rules

The mixed member rules, which took effect from December 2013, were introduced to stop partnership and LLP profits being diverted to corporate partners, who pay a lower rate of Corporation Tax than the individual partners, who were subject to a higher rate of Income Tax.

Broadly,  profits allocated to a corporate entity are taxable on the individual partner where the following conditions are satisfied:

• Deferred Profit – Profits are allocated to a corporate partner, and this essentially represents profits that would ordinarily be due to an individual partner. As a result, the individual’s profit share and total tax liabilities are lower than they would have been without this arrangement;
• Power to Enjoy – The corporate partner’s profit share exceeds a ‘reasonable’ return, and the individual can enjoy the profit allocated to that corporate. These rules are widely drawn, but where the individual and the corporate are connected, and the individual can benefit from the profits allocated to the corporate, this condition would be met.

The HFFX LLP Case

HFFX LLP, a foreign exchange trading firm, operated a deferred remuneration arrangement known as a Capital Allocation Plan (CAP). Under this structure, a portion of members’ remuneration was retained by a corporate member (GSAM) and invested. After a three‑year period, the proceeds were returned to HFFX as “Special Capital” and could be allocated to individual members at GSAM’s discretion.

Although members received indicative allocation letters, GSAM retained absolute discretion as to whether and how much capital would ultimately be allocated, taking into account factors such as individual performance and firm results. Crucially, there was no contractual entitlement for members to receive the amounts indicated.

HMRC argued that these allocations should be taxed as profit shares under the mixed members rules.   Alternatively, HMRC contended that amounts actually received should be taxed as miscellaneous income.

The Supreme Court’s decision

The Court rejected HMRC’s primary argument under the mixed-member rules. It held that, for an amount to constitute a partner’s share of profits, the partner must have a contractual right during the relevant accounting period to that share.

Because HFFX members had no enforceable entitlement—only a discretionary expectation—the indicative allocations did not qualify as profit shares. The Court stressed that profit-sharing arrangements must allow one to determine definitively, during the relevant period, what portion of profits belongs to each partner.

However, the Court upheld HMRC’s alternative position. It ruled that the payments ultimately received by members were taxable as miscellaneous income. A key question was whether these payments arose from a “source” of income. The Court adopted a broad interpretation, concluding that the decision-making process of GSAM and the LLP constituted a sufficient source.

Therefore, even without a contractual entitlement, the combination of the LLP agreement and discretionary allocation decisions created a taxable income source when payments were made.

5 key Implications for taxpayers

This judgment has several significant implications for LLPs, partnerships, and professional firms using incentive or deferred compensation arrangements:

1. Contractual entitlement is key for profit share treatment
   The decision confirms that only amounts supported by a clear contractual right during the relevant accounting period will be treated as profit shares under the mixed member rules. Structures relying on discretionary or contingent allocations should fall outside this provision.
2. Discretionary payments can still be taxable
   Importantly, the Court’s wide interpretation of “source” means that discretionary payments are not tax-free simply because they lack legal enforceability. Where there is an identifiable mechanism or activity leading to payment, this can constitute a taxable source.
3. Increased risk of dual-layer taxation
   The arrangement in HFFX involved corporation tax at the corporate member level, followed by income tax when funds were distributed to individuals. The Court acknowledged that this outcome is akin to dividend taxation, potentially leading to higher overall tax burdens for similar structures.
4. Limited scope for “voluntary payment” arguments
   The judgment narrows the circumstances in which taxpayers can argue that payments are non-taxable voluntary receipts. Only genuine gifts—where there is no right even to be considered for payment—are likely to fall outside the miscellaneous income provisions.
5. Need for careful structuring of incentive schemes
   Partnerships using deferred remuneration or carried-interest style arrangements must carefully consider whether participants have enforceable rights and how discretion is exercised. Even well-designed incentive plans intended to defer or mitigate Income Tax may still result in taxable income.

Conclusion

The Supreme Court’s decision provides clarity but also highlights the limits of tax planning using discretionary allocation mechanisms. While the absence of a contractual entitlement prevents amounts from being taxed as profit shares, it does not eliminate tax exposure. Instead, such receipts are likely to be caught by the broad sweep of miscellaneous income rules.

For taxpayers and advisers, the key takeaway is that form and substance both matter: removing legal entitlement may change the category of taxation, but it will not necessarily prevent a tax charge arising. If you have any queries about mixed member rules or partnership taxation please do not hesitate to get in contact with Jill Walker, a member of our professional services team, or your usual AAB contact.