What Is a Service Level Agreement (SLA)?

A service level agreement (SLA) is a documented commitment that defines the standard of service a provider must deliver - what is covered, how performance is measured, and what happens when a target is missed. SLAs sit inside contracts with IT suppliers, equipment servicing firms, and facilities providers, and the same idea is used internally to set targets for a company’s own service desk.

What an SLA covers

A usable SLA answers five questions in writing:

• Scope - which services, sites, or assets are covered, and which are explicitly excluded.
• Standards - the measurable targets: response times, resolution times, uptime commitments, scheduled visit frequency.
• Measurement - how and when performance is counted: working hours or calendar hours, who runs the clock, what data settles a dispute.
• Priorities - most SLAs grade incidents (a production-stopping failure gets a faster clock than a flickering screen).
• Remedies - what happens on a miss: service credits, fee reductions, escalation, or termination rights.

The weakest SLAs fail on measurement: targets exist, but nobody records actual performance, so the agreement is unenforceable in practice.

Response time vs resolution time

These two clocks are the heart of most maintenance and support SLAs, and confusing them is the classic mistake. Response time is how fast the provider acknowledges the issue and begins work. Resolution time is how long until the thing is fixed. A contract might commit a provider to respond to a critical fault within four working hours and restore operation within one working day - while a low-priority cosmetic issue waits for the next scheduled visit. If your contract only specifies response time, you have bought a fast phone call, not a fast repair.

Common SLA metrics

Beyond the two clocks, SLAs for equipment and IT typically measure first-time fix rate (was a second visit needed?), uptime or availability over a period, adherence to the preventive maintenance schedule, and parts lead time - how quickly a replacement component arrives, which often depends on the provider’s own spare parts management. For safety-critical kit the SLA is frequently a calibration or inspection commitment: gas detectors, for instance, commonly sit under a contract that guarantees calibration on a fixed cycle and a loan unit while a detector is away.

Internal SLAs and the service desk

The same discipline applies inside an organisation. An internal SLA might say that fault reports are acknowledged within four working hours, replacement equipment is issued within a day, or unplanned maintenance on critical assets always outranks routine jobs in the queue. Internal SLAs have no penalty clause - their value is clarity. Employees know what to expect, the team triages by agreed priority instead of by who shouts loudest, and missed targets become a staffing or process conversation backed by data.

Common SLA mistakes

The recurring failures are predictable: clocks that are ambiguous (does “four hours” include the night shift?), no exclusion list (so misuse and consumable wear get argued case by case), penalties that exist on paper but are never invoked, and SLAs written once and never revisited as the asset base changes. Read the measurement clause as carefully as the targets - a generous target measured by the provider’s own unaudited numbers protects nobody.

Related terms

• Planned vs Unplanned Maintenance - the work types an SLA’s clocks usually govern
• Equipment Servicing - the routine visits many SLAs schedule and guarantee
• Preventive Maintenance - the proactive programme SLAs often commit a provider to
• Corrective Maintenance - the repair work response and resolution times apply to
• Spare Parts Management - the stocking discipline behind fast resolution times