Service Level Agreement (SLA)

A service level agreement is the part of a contract that commits a supplier to measurable standards: how quickly they will respond, how quickly they will fix things, and how much of the time a system will be available.

The important word is measurable. A commitment to "prompt support" is not an SLA. A commitment to respond to a critical issue within two business hours is.

The three things it should cover

Response time. How long before a human acknowledges the problem and starts work. Usually banded by severity.

Resolution time, or a target. Harder to commit to honestly, because some problems are genuinely unpredictable. A reasonable supplier commits firmly to response and gives a target with an escalation path for resolution. Be slightly wary of anyone promising a guaranteed fix time for everything, because they have either priced very defensively or will define their way out of it.

Availability. The percentage of time a system is up, usually expressed as 99.9 per cent or similar. Worth translating: 99.9 per cent allows around 43 minutes of downtime a month. 99 per cent allows over seven hours.

The definitions that actually matter

Most SLA disputes are not about the numbers. They are about definitions.

What counts as critical? If the supplier decides severity, the clock starts when they say it does. Agree the definitions in writing, with examples.

When does the clock run? Business hours, and whose? A two-hour response is a very different promise inside a 9-to-5 window than around the clock.

What is excluded? Third-party outages, changes you made, problems in systems they do not manage. Some exclusions are entirely fair. A list long enough to cover every plausible incident is not.

What happens when it is missed? An SLA with no consequence is a statement of intent. Service credits are the usual remedy, and they are typically small; their value is as a trigger for a conversation rather than as compensation.

What it does not give you

An SLA measures responsiveness, not usefulness. A supplier can hit every target and contribute nothing, because a response-time commitment says nothing about whether anyone is thinking about your business between tickets.

That is a different thing, and it is worth asking for separately: a named contact, a scheduled review, and someone raising problems before you notice them.