Fee Models for Arbitrators: Hourly Rates, Ad Valorem Fees, or Fixed Fees

The 2025 revision to the Hong Kong International Arbitration Centre (HKIAC) Administered Arbitration Rules introduced a new Schedule of Fees based on capped hourly rates, replacing the previous ad valorem (value-based) scale for tribunal costs. This change, effective 1 June 2025, directly affects how parties budget for disputes. The HKIAC’s shift mirrors a global trend, but the specific fee model an arbitrator uses—hourly rates, ad valorem fees, or fixed fees—determines cost predictability, risk allocation, and the incentive structure for efficient case management. Choosing the wrong model for a given dispute can lead to budget overruns or procedural deadlock. This article explains the three primary fee models available under Hong Kong law and institutional rules, their practical implications for commercial parties, and the procedural steps to negotiate or challenge them.

Hourly Rates: The Default Under Most Institutional Rules

The hourly rate model is the most common fee structure for arbitrators in Hong Kong, particularly under the HKIAC Rules and the UNCITRAL Rules (as adopted by the Hong Kong Arbitration Ordinance, Cap. 609). Under this model, the arbitrator is paid for actual time spent on the case, multiplied by an agreed hourly rate.

How the Rate Is Set and Approved

The HKIAC Rules (2025 Revision) provide that the tribunal’s hourly rates must be disclosed to the parties at the outset and approved by the HKIAC Council. The 2025 Schedule caps rates at HKD 6,500 per hour for co-arbitrators and HKD 8,000 per hour for sole arbitrators or presiding arbitrators. These caps apply to arbitrations commenced on or after 1 June 2025. Parties may agree to higher rates, but the HKIAC will not approve a rate above the cap without exceptional justification.

Cost Control Mechanisms

The primary risk with hourly rates is cost uncertainty. The HKIAC addresses this through two mechanisms. First, the tribunal must submit periodic fee estimates to the HKIAC Secretariat, which are shared with the parties. Second, the HKIAC may reduce the arbitrator’s claimed fees if the hours appear excessive relative to the complexity of the case. Section 34 of Cap. 609 also empowers the Court of First Instance to review arbitrator fees on application by a party, though this remedy is rarely used in practice.

When Hourly Rates Are Appropriate

Hourly rates suit complex, document-heavy disputes where the volume of work is unpredictable. Examples include construction disputes under the Hong Kong Institute of Architects standard forms or shareholder oppression claims under the Companies Ordinance (Cap. 622). The model aligns the arbitrator’s incentive with thoroughness, but it can discourage early settlement if the arbitrator has no financial incentive to conclude the case quickly.

Ad Valorem Fees: The Old HKIAC Default and Its Legacy

The ad valorem model calculates arbitrator fees as a percentage of the amount in dispute. This was the default under the HKIAC’s pre-2025 Rules for arbitrations where the amount in dispute exceeded HKD 2 million. The 2025 revision removed this as a default, but parties can still agree to ad valorem fees by express provision in the arbitration agreement or by subsequent consent.

How the Percentage Scale Works

Under the former HKIAC Schedule, fees were calculated on a sliding scale: 1.5% on the first HKD 5 million, 0.5% on amounts between HKD 5 million and HKD 50 million, and 0.2% on amounts above HKD 50 million, subject to a maximum of HKD 25 million for a sole arbitrator. These percentages remain available as a reference point. The Hong Kong Institute of Arbitrators (HKIArb) published a similar scale in its 2023 Guidance Note on Fee Structures.

The Risk of Over- or Under-Compensation

The ad valorem model creates a direct link between the monetary value of the claim and the arbitrator’s compensation. For a dispute worth HKD 100 million, a sole arbitrator might earn HKD 1.5 million under the old scale—far more than the actual time spent would justify. Conversely, for a low-value but factually complex case (e.g., a HKD 500,000 intellectual property dispute with extensive documentary evidence), the ad valorem fee may be too low to attract a qualified arbitrator. The HKIAC’s 2024 Consultation Paper on Fee Reform identified this mismatch as a key driver of the rule change.

Procedural Steps to Elect Ad Valorem Fees

If parties wish to retain the ad valorem model, they must include a clause such as: “The arbitrator’s fees shall be calculated in accordance with the HKIAC’s ad valorem scale in force at the date of commencement of the arbitration.” The arbitration agreement should specify which scale applies and whether the cap on maximum fees is waived. The HKIAC will not override a clear party agreement, but it will require confirmation that both sides understand the cost implications.

Fixed Fees: The Emerging Alternative for Specific Dispute Types

Fixed fees are a lump-sum payment for the entire arbitration, regardless of the time spent or the amount in dispute. This model is uncommon in Hong Kong institutional arbitration but is gaining traction in expedited procedures and domestic arbitrations under the HKIAC’s Low-Value Disputes Protocol (effective 2024).

How Fixed Fees Are Structured

A fixed fee arrangement typically covers all stages of the arbitration: case management conference, written submissions, evidential hearing, and award drafting. The fee is agreed between the parties and the arbitrator before appointment. The HKIAC’s 2024 Protocol for Low-Value Disputes (claims under HKD 2 million) recommends a fixed fee of HKD 80,000 to HKD 150,000 for a sole arbitrator, depending on complexity. The arbitrator bears the risk of overruns.

Advantages and Risks for Parties

The main advantage is cost certainty. A party facing a HKD 1.5 million breach of contract claim knows the arbitrator’s fee will be, for example, HKD 100,000, not an open-ended hourly bill. The risk is that the arbitrator may cut corners to stay within the fixed fee, particularly on procedural fairness. Section 46 of Cap. 609 requires the tribunal to act fairly and impartially, but a fixed fee creates no financial incentive to conduct a thorough hearing.

When Fixed Fees Fail

Fixed fees are unsuitable for multi-party arbitrations, cases with likely interlocutory applications (e.g., applications for interim measures under Section 35 of Cap. 609), or disputes where the amount in dispute is likely to change. The HKIAC’s 2025 Guidance Note on Fee Arrangements warns that fixed fees should not be used where the arbitration involves more than two parties or where the claim value exceeds HKD 10 million.

Choosing the Right Model: Practical Considerations for Parties

The choice of fee model should be made at the time of drafting the arbitration agreement or, at the latest, during the first case management conference. The HKIAC Rules (2025 Revision) require the tribunal to discuss fee arrangements with the parties at the preliminary meeting.

Factor 1: Amount in Dispute and Complexity

For claims under HKD 5 million, fixed fees offer the best cost predictability. For claims between HKD 5 million and HKD 50 million, hourly rates provide flexibility. For claims above HKD 50 million, ad valorem fees may be attractive if the case is straightforward, but hourly rates are safer if the dispute is document-intensive.

Factor 2: Number of Parties and Counsel

Multi-party arbitrations (three or more parties) almost always require hourly rates. The HKIAC’s 2025 Fee Schedule explicitly states that fixed fees are not available for multi-party cases. Ad valorem fees can work but require careful allocation of the fee among parties.

Factor 3: Institutional Oversight

If the parties choose ad valorem or fixed fees, they should ensure the institution (HKIAC, ICC, SIAC) has a mechanism to review the reasonableness of the fee. The HKIAC’s 2025 Rules provide for such review only for hourly rates. Parties relying on ad valorem or fixed fees under the HKIAC should include a clause requiring the HKIAC Council to approve the fee arrangement.

Actionable Takeaways

1. Include a fee model clause in your arbitration agreement that specifies hourly rates, ad valorem fees, or fixed fees, and reference the applicable HKIAC schedule or institutional rule.
2. For disputes under HKD 2 million, use the HKIAC Low-Value Disputes Protocol’s fixed fee to eliminate cost uncertainty.
3. For claims between HKD 5 million and HKD 50 million, hourly rates under the 2025 HKIAC cap of HKD 6,500 per hour provide the best balance of flexibility and control.
4. Never agree to ad valorem fees without a cap on the maximum fee amount, as the old HKIAC scale can produce disproportionately high compensation.
5. At the first case management conference, confirm the fee model in writing and obtain the tribunal’s estimate of total fees, which the HKIAC Secretariat will monitor.

This does not constitute legal advice. Consult a solicitor for your specific case.