A service level agreement (SLA) is the part of a service contract that defines what level of service a provider commits to, how that service is measured and reported, what each party is responsible for, and what remedies apply when the provider misses its targets. Typical SLAs cover availability, performance, support response and time to restore service. An SLA usually sits alongside, or as a schedule to, a master services agreement (MSA) and the order forms for each service.
At a glance
- An SLA turns a provider’s service promises into measurable, contractual commitments.
- Common metrics include availability or uptime, latency and packet loss, response time and time to restore.
- Remedies are usually service credits, often capped and subject to claim procedures; termination rights for repeated failures need to be negotiated separately.
- Definitions, measurement methods and exclusions often matter more than the headline target.
- SLAs vary widely by provider and service tier, so read the actual document rather than the marketing summary.
What problem it solves
Without an SLA, a provider’s commitments are whatever its sales materials say, and when service fails there is no agreed standard to point to and no remedy. An SLA gives both sides a shared definition of good service, a way to measure it and a process for when things go wrong.
For buyers, a well-written SLA does three things: it sets expectations you can plan around, it gives you evidence and leverage when service falls short, and it creates incentives for the provider to invest in reliability. A poorly written one does little more than decorate a proposal with an impressive-looking percentage.
How it works
Service definition and scope. The SLA describes the service covered, the locations, users or systems in scope, and any service tiers.
Targets and measurement windows. Each metric has a target and a period, such as 99.9% availability measured monthly. Network services often add latency, jitter and packet loss targets; voice services may use call quality measures such as mean opinion score (MOS); support services set response and resolution times by severity.
Severity levels and escalation. Incidents are classified by business impact, with response and restore targets for each level and an escalation matrix naming who gets involved and when.
Measurement and reporting. The SLA says how metrics are captured, often from the provider’s own monitoring, where they are reported, and what evidence you can see. Some contracts allow customer monitoring data to be used in disputes; many don’t.
Exclusions. Planned maintenance, customer-caused problems, force majeure events and issues outside the provider’s network are commonly excluded. How broadly these are written can change what the SLA is worth.
Remedies. Service credits are the most common remedy, usually calculated on a sliding scale, capped at a share of the monthly charge, and often requiring you to submit a claim within a set period. A chronic outage clause may allow termination without penalty after repeated failures.
When it matters for buyers
- When comparing proposals. Two providers quoting 99.99% may mean very different things depending on how downtime, measurement and exclusions are defined.
- When buying critical services. Internet access, network, voice, hosting and security services that your business depends on deserve the closest SLA review.
- When outsourcing IT functions. Managed service and support contracts rely on SLAs for response and resolution times and service reporting.
- When a contract renews. Renewal is the moment to fix weak definitions, add missing metrics and negotiate stronger remedies, based on how the service actually performed.
- When an outage happens. Knowing your SLA’s claim process and deadlines determines whether you receive any credit at all.
Providers that commit to strong SLAs usually back them with round-the-clock monitoring, such as managed network services and dedicated internet access with business-grade support. For more on reviewing contract terms, see what to look for before signing an IT contract.
Questions to ask vendors
- How exactly is downtime defined: total outage only, or also severe degradation?
- How is each metric measured, over what period, and can we see the underlying data?
- What is excluded, and how much planned maintenance is allowed, and when?
- What are the response and restore targets for each severity level, and are they measured to response or to resolution?
- How are credits calculated and capped, and do we have to claim them? By when?
- Do repeated breaches give us the right to terminate without penalty?
- Does the SLA cover the full path we depend on, such as the local access circuit, or only part of it?
- What root-cause reporting do you provide after a major incident?
Negotiating and operating an SLA
Start from what your business actually feels when a service fails, and focus on a few metrics that reflect it, such as time to restore a critical site or call quality during business hours. Push for clear definitions, transparent measurement, limited exclusions and remedies that scale with impact, including termination rights for chronic failures. Where you can, run your own monitoring rather than relying only on the provider’s reports, track performance monthly, file credit claims on time, and bring the data to quarterly reviews and renewals.
How it differs from an SLO
A service level objective (SLO) is a measurable target a team sets for its own service, such as 99.9% of requests succeeding over 30 days. It carries no contractual remedy; missing it triggers internal action rather than credits. An SLA is the external, contractual commitment, with defined remedies. Providers often set internal SLOs stricter than their SLAs so they can fix problems before a contractual breach. Inside an organization, an operational level agreement (OLA) between internal teams plays a similar supporting role, describing what each team must deliver so the customer-facing SLA can be met. Measures such as mean time to recovery (MTTR) can appear in all three.
Problems this helps with
- Provider claims great uptime but outages keep hurting us
- Can't tell what a provider has actually committed to
- Credits are tiny compared with the cost of an outage
- Need contract terms that hold a provider to account
