Service Level Agreement (SLA): A Legal Drafting Guide for Hong Kong B2B Contracts

A Service Level Agreement is a contractual document, signed between a service provider and a customer, that defines the level of service expected, the way it is measured and the remedies available to the customer if the agreed levels are not met. SLAs are most common in technology and outsourcing contracts but apply to any B2B service relationship where measurable performance is critical.

An SLA may sit as a standalone agreement, as a schedule to a Master Service Agreement (MSA), or as a section within a single integrated contract. In each case, the SLA’s function is the same: to translate the high-level promise of service delivery into specific, measurable, enforceable commitments.

These terms are sometimes used loosely. Each has a distinct function in the contractual architecture.

SLA structure varies according to the customer relationship. Three models dominate.

A single SLA covering all services provided to one specific customer. The customer negotiates bespoke metrics tailored to its operational needs. Common in large enterprise outsourcing arrangements.

A single SLA covering one specific service provided to all customers of that service. Common in standardised cloud, SaaS and telecom offerings. The customer receives the published service levels with limited room for variation.

A layered structure combining corporate, customer and service-level commitments. Common in large outsourcing deals where multiple business units consume the same shared services with differentiated treatment.

A complete SLA contains the following building blocks. Missing any of them creates a gap that the parties will eventually need to fill, often in less favourable circumstances than the original drafting.

While the legal architecture of an SLA is what makes it enforceable, the metrics are what give it commercial meaning. The metrics chosen must be measurable, attributable, and proportionate to the service criticality.

A workable process for drafting an SLA from scratch, or for reviewing a counterparty’s draft.

1. Define the service. Be explicit on what is in scope and what is excluded. Reference the SOW or service catalogue where appropriate.
2. Verify the achievable service levels. Performance benchmarks should be informed by operational data, not by aspirational marketing claims.
3. Determine the metrics. Each metric must be measurable, attributable to the provider, and material to the customer’s business.
4. Define the measurement methodology. Specify the monitoring tool, the calculation formula, the data source and the reporting cadence.
5. Set the remedies. Service credits, fee rebates or termination rights, calibrated to the severity and frequency of the breach. Avoid disproportionate penalty figures.
6. Add governance. A periodic service review meeting, escalation paths, change control for SLA modification.
7. Layer the boilerplate. Indemnities, limitation of liability, confidentiality, governing law, dispute resolution.
8. Review and iterate. SLAs need testing against realistic operational scenarios before signing.

Hong Kong SLAs are governed by the general common law of contract, refined by case law and overlaid by specific statutes. Four areas deserve particular attention.

Hong Kong common law, following the English Supreme Court decision in Cavendish v Makdessi and longstanding authority from Dunlop Pneumatic Tyre v New Garage, distinguishes between liquidated damages (enforceable) and penalties (unenforceable). A service credit clause that bears no genuine relation to the loss likely to be suffered, and that operates ‘in terrorem’ on the breaching party, may be struck down as a penalty. The modern test asks whether the clause protects a legitimate commercial interest of the innocent party and whether the sum stipulated is extravagant or unconscionable in relation to that interest.

Limitation of liability clauses in SLAs are subject to the reasonableness test under Cap. 71 in many B2B contexts. The factors in Schedule 2 include the bargaining position of the parties, whether the customer received an inducement to accept the term, the customer’s knowledge of the term, and whether the goods were manufactured to the customer’s special order. A liability cap that fails the reasonableness test will not be enforced. See our commercial agreements practice for the broader framework on Cap. 71.

Where the service involves processing personal data, the customer (as data user) remains responsible under the PDPO for the acts of its data processors. SLAs in cloud, BPO and managed services contexts should include clear obligations on data security, breach notification, sub-processing controls, and PDPO-aligned contractual safeguards.

Hong Kong common law does not imply a general doctrine of force majeure into contracts. Express force majeure clauses are essential where the parties wish to suspend performance obligations during specified disrupting events. Material change clauses can also be used to allow renegotiation in defined long-term contexts.

• Ambiguous metrics. ‘Reasonable response time’ is not a metric. Quantify everything.
• No measurement methodology. If the contract does not say how to calculate the metric, the parties will dispute the calculation.
• Missing exclusions. Scheduled maintenance, third-party network issues and force majeure events must be expressly excluded from SLA calculations.
• Penalty clauses dressed up as service credits. A credit equal to 100% of monthly fees for a single missed metric, with no relation to actual customer loss, is likely a penalty and unenforceable.
• No governance mechanism. Without periodic service review and a change control process, the SLA degrades over time as operational reality drifts from contract.
• No earn back. Provider has no path to recover credits even after sustained over-performance, leading to deteriorating commercial relations.

When the service provider is acquired or undergoes a change of control, the customer often asks whether the SLA continues unaffected. The answer turns on three issues. First, the assignment and change-of-control clause in the underlying contract or MSA. Second, whether the SLA contains its own assignment provisions. Third, whether the customer has separately agreed to consent or has bargained for a termination right on change of control.

Well-drafted MSAs include a change-of-control termination right for the customer, particularly where the provider’s identity is material (specialist services, sole supplier of critical infrastructure). Where the right is not exercised, the SLA transfers with the underlying contract by novation or by operation of the assignment clause.