In the Microsoft Volume Licensing Service Level Agreement for Microsoft Online Services document, dated August 1, 2023, the terms for each of the individual cloud services are listed with the following information:

• Downtime Specifies exactly what type or types of service interruption legally constitute downtime in the terms of the agreement. Some of the definitions of downtime for cloud services included in Microsoft 365 are shown in Table 4-5.
• Monthly Uptime Percentage Specifies the formula by which the percentage of uptime is calculated for each month, considering the number of minutes the service was considered to be down and the number of user licenses affected by the outage. For example, the following formula subtracts the total number of downtime minutes for all the users from the total user minutes and calculates a percentage from that:

User Minutes−Downtime MinutesUser Minutes

• Service Credit Specifies the percentage of the monthly subscription fee that will be credited to the subscriber’s account based on the calculated monthly uptime percentage. For example, Microsoft’s SLA for Microsoft 365 Apps for Enterprise guarantees 99.9 percent uptime, so the service credit for months that do not meet that percentage is calculated as shown in Table 4-6. Other Microsoft services can have different SLA guarantees, such as Azure Active Directory, which has a 99.99 percent guaranteed uptime.
• Additional Terms Identifies other parts of the document that might define other conditions constituting a refundable service outage. For example, a failure of Exchange Online to detect viruses or filter spam as agreed in the SLA can qualify for a service credit, even if no downtime occurs.

TABLE 4-5 Definitions of downtime in the Microsoft Volume Licensing Service Level Agreement for Microsoft Online Services

TABLE 4-6 Service credit for monthly uptime percentages in the Microsoft Volume Licensing Service Level Agreement for Microsoft 365 Apps for Enterprise

Microsoft requires subscribers to file a claim for service credits containing evidence of the outages, as described in the following SLA excerpt:

In order for Microsoft to consider a claim, you must submit the claim to customer support at Microsoft Corporation including all information necessary for Microsoft to validate the claim, including but not limited to: (i) a detailed description of the Incident; (ii) information regarding the time and duration of the Downtime; (iii) the number and location(s) of affected users (if applicable); and (iv) descriptions of your attempts to resolve the Incident at the time of occurrence.

Generally speaking, it appears as though the SLA for Microsoft’s online services is rarely even needed. For example, Table 4-7 lists the worldwide quarterly uptime percentages for the Microsoft 365 cloud services in recent years, and none of the figures even comes close to dropping below the 99.9 percent uptime guaranteed for most of the Microsoft 365 services. This is not to say that there weren’t a few isolated outages resulting in service credits, but the overall record for the Microsoft 365 products is impressive.

TABLE 4-7 Quarterly Uptime Percentages for Microsoft 365, 2019 to 2023