SLA
An SLA (Service Level Agreement) is a contract between a provider and a customer that defines measurable quality criteria for a service – e.g. availability, response times or support level.
When an IT system fails, every minute counts. A Service Level Agreement (SLA) bindingly defines what level of service a provider guarantees – and what happens if they do not meet it. SLAs create transparency, planning certainty and trust between client and provider. From cloud service availability to IT support response time – SLAs are the foundation of professional IT services.
What is SLA?
A Service Level Agreement (SLA) is a formal, usually contractually binding agreement that defines concrete, measurable KPIs for a service. Typical SLA metrics include availability (e.g. 99.9%), maximum response times for incidents, resolution times by priority and performance metrics such as response times. SLAs also define escalation, reporting and consequences of non-compliance (penalties or service credits). Types: customer-specific SLAs, service-specific SLAs and multi-level SLAs. SLAs are a core element of ITIL and other IT service management frameworks.
How does SLA work?
Provider and customer agree on concrete, measurable criteria and document them in the contract. Monitoring systems watch the agreed metrics continuously. Regular SLA reports show the customer whether targets are met. If values are missed, defined escalation and possibly financial compensation (service credits) apply. Both parties review SLAs in regular service reviews and adjust them to changing requirements.
Practical Examples
A cloud provider guarantees 99.95% availability per month – max. approx. 22 minutes downtime.
An IT support contract requires critical incidents to be responded to within 15 minutes and resolved within 4 hours.
A hosting SLA states that if availability is below target, a proportional credit (service credit) is applied automatically.
A managed service provider commits to monthly security updates within 48 hours of release.
A software maintenance contract defines response and resolution times for bugs by priority (critical, high, medium, low).
Typical Use Cases
Companies contractually secure guaranteed minimum availability for business-critical IT systems
Managed service providers define clear scope and quality standards for customers
Internal IT agrees SLAs with business units to set expectations and priorities
Cloud migrations are backed by SLAs guaranteeing performance, availability and data security
Software maintenance contracts use SLAs for binding response and resolution times
Advantages and Disadvantages
Advantages
- Planning certainty: Both sides know exactly what level of service to expect
- Measurable quality: KPIs make service quality objectively verifiable
- Accountability: Clear consequences when targets are not met
- Professionalization: SLAs support structured, service-oriented collaboration
- Trust: Transparent agreements strengthen the business relationship
Disadvantages
- Complex negotiation: Defining realistic, measurable metrics requires experience and alignment
- Cost rises with stricter targets: 99.99% availability is much more expensive than 99.5%
- False security: An SLA does not guarantee availability, only consequences when it fails
- Administrative effort: Monitoring, reporting and regular reviews need resources on both sides
Frequently Asked Questions about SLA
What does 99.9% availability mean?
What happens when an SLA is breached?
How do you define a good SLA?
Related Terms
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