Microsoft 365 business outage claim tool
Microsoft 365 Outage SLA Credit Estimator for EX1550543
Estimate whether your organization’s Exchange Online availability may fall below Microsoft’s published service-credit thresholds for the November 2026 outage. Estimate uptime using affected user-minutes, model a potential service-credit amount against the eligible Exchange Online fee, and prepare a claim-review draft for Microsoft Support or your provider.
Built for Microsoft 365 business, enterprise, education and government administrators. This is not for personal Outlook.com or Microsoft 365 Personal and Family subscriptions. It is an independent estimator, not a Microsoft eligibility decision, and it is not affiliated with Microsoft.
Microsoft 365 SLA Credit Estimator
Use tenant-specific user-minute evidence to estimate Exchange Online uptime and prepare a claim-review draft.
Enter your tenant and outage details
Example values are pre-filled (200 users, 50 of them down for 180 minutes) so you can see how the estimate works. Replace them with the actual Exchange Online impact recorded for your organization.
How the Microsoft 365 SLA estimator works
The Exchange Online availability estimate is based on user-minutes, not simply the number of hours shown in a headline about a global outage.
| Step | What it means |
|---|---|
| Total user-minutes | Minutes in the applicable period multiplied by the total users. |
| Downtime user-minutes | For each qualifying incident, downtime minutes multiplied by the users impacted. Combine repeated events per user without counting overlapping minutes twice. |
| Monthly uptime | (Total user-minutes minus downtime user-minutes) divided by total user-minutes, multiplied by 100. |
| Illustrative credit amount | Applicable fees for the affected service multiplied by the relevant service-credit percentage. Microsoft’s partner guidance says credits are prorated by the service affected and the duration of the outage, so the final credit can be lower than this illustration. |
More example scenarios (30-day month, 200 users, qualifying downtime only):
| Scenario | Downtime user-minutes | Estimated uptime | Tier used by estimator |
|---|---|---|---|
| 50 users down 180 minutes | 9,000 | 99.8958% | 25% |
| All 200 users down 30 minutes | 6,000 | 99.9306% | 0% |
| All 200 users down 180 minutes | 36,000 | 99.5833% | 25% |
| All 200 users down 600 minutes | 120,000 | 98.6111% | 50% |
| All 200 users down 2,200 minutes | 440,000 | 94.9074% | 100% |
Rule of thumb for a 30-day month if every user is affected: more than 43.2 minutes of qualifying downtime per user takes uptime below 99.9%, more than 432 minutes (7.2 hours) takes it below 99%, and more than 2,160 minutes (36 hours) takes it below 95%. If only some users are affected, more minutes are needed.
Which November 2026 Microsoft 365 incident should you enter?
EX1550543 is the primary Exchange Online incident reference for the November 2026 mailbox-connectivity disruption. Microsoft’s incident information lists multiple potentially affected connection methods, but the public incident scope is not itself a tenant-level SLA calculation.
MO1550821 is a related wider Microsoft 365 advisory. Microsoft’s partner guidance says advisory incidents are not typically eligible for SLA credits, so use it as supporting context only and do not add its full duration as a second Exchange Online outage on top of EX1550543. If another distinct Exchange Online incident affected your tenant in the same applicable month, include its qualifying user-minutes and list its incident ID in the claim draft.
Public start and recovery times are not a substitute for the affected-user evidence and qualifying downtime recorded for your own tenant. Check your tenant’s Service Health history and the final incident post before filing, because the incident may still be updated.
Who should use this Microsoft 365 SLA credit estimator?
This estimator is designed for administrators of eligible organizational Microsoft Online Services subscriptions. It is not a consumer refund checker. Before estimating a credit, confirm all of the following:
- Your subscription is an eligible commercial Microsoft Online Services offer covered by an SLA.
- The affected service is Exchange Online, and the problem meets the SLA definition of downtime.
- You have tenant-specific evidence of which users experienced qualifying Exchange Online downtime under the applicable SLA definition, and for how long.
- The failure was not caused by an excluded condition such as an ISP or other network outside Microsoft’s boundary, tenant misconfiguration, an unsupported extension or an on-premises dependency.
- You can identify the applicable Exchange Online service-fee portion rather than using the full suite invoice as the credit base.
Using personal Outlook.com or Microsoft 365 Personal or Family?
This estimator is for eligible commercial Microsoft Online Services subscriptions with tenant-level evidence. Personal Outlook.com and Microsoft 365 Personal or Family users should not assume they qualify for the commercial Exchange Online SLA credit process, and a public outage does not create an automatic personal cash refund. If you use a personal account, check Microsoft 365 service status and use Microsoft Outlook consumer support for account-specific help.
Exchange Online service-credit thresholds used by this estimator
The tier schedule below is an estimate aid based on the Exchange Online service-credit structure and must be checked against the SLA edition incorporated into your subscription agreement. Microsoft’s licensing library lists the English Worldwide Online Services SLA dated November 1, 2026 as its most recent edition as of November 13, 2026, alongside archived editions. The thresholds below are modeled for estimation only. Confirm the Exchange Online terms, eligibility exceptions, and applicable service-credit schedule in the SLA incorporated into your subscription agreement. These are potential service credits against eligible service fees, not automatic cash refunds.
| Estimated Exchange Online uptime | Tier used by this estimator |
|---|---|
| 99.9% or higher | 0% |
| Below 99.9% but at least 99% | 25% |
| Below 99% but at least 95% | 50% |
| Below 95% | 100% |
Open the official Microsoft SLA library to review the dated document and its archive. Your signed agreement, order form, offer type, and incorporated SLA version control the final interpretation. If the SLA you rely on differs from this table, the SLA controls.
Prepare your Microsoft 365 outage claim
Use the result above as a working estimate. Generate a claim-review draft you can edit and submit through the correct support channel. This tool does not submit a ticket or contact Microsoft.
What to collect before requesting an SLA credit
Claim-window reference, and why to file early: Microsoft’s Partner Center guidance for Cloud Solution Provider requests says credit requests for services other than Azure must be submitted within one month from the end of the billing month in which the incident occurred. For a calendar-month billing period ending November 30, 2026, the conservative reading is December 30, 2026. This is CSP guidance, not a universal deadline for every purchase channel, and your billing month may differ. Direct and volume-license customers should confirm the deadline in the SLA and agreement that govern their subscription. Do not wait for the reference date.
Microsoft 365 SLA credit estimator: FAQs
Can every Microsoft 365 customer claim a credit for EX1550543?
No. The public incident shows that Microsoft identified a service issue, but each claim depends on the applicable commercial subscription, the affected service, qualifying downtime, the relevant SLA version, and evidence that the tenant was impacted. Consumer Outlook.com and Microsoft 365 Personal or Family users should not use this commercial Exchange Online SLA estimator to assume eligibility.
How much downtime drops Exchange Online below 99.9% in a month?
In a 30-day month, 99.9% uptime allows about 43.2 minutes of qualifying downtime per user if every user is affected. Falling below 99% takes more than 432 minutes (7.2 hours), and below 95% more than 2,160 minutes (36 hours), using the thresholds this estimator applies. If only some users are affected, more minutes are needed.
Does a long global outage automatically mean a 50% credit?
No. The estimate uses affected user-minutes across the applicable period. If only some users were affected, or users experienced shorter or intermittent failures, the estimated uptime can be materially higher. Microsoft also determines which periods count as qualifying downtime.
Should I include another Exchange Online outage from the same month?
Yes, if it separately meets the downtime definition in the SLA that applies to your subscription and affected your tenant. Include all qualifying, non-overlapping user-minutes for the same applicable period. Do not count the same user-minute twice, and list the additional incident ID in the claim draft.
Can personal Outlook.com users claim this commercial SLA credit?
This estimator is not for personal Outlook.com or Microsoft 365 Personal or Family subscriptions. Personal users should check Microsoft’s service status and use Outlook consumer support. Do not assume that a public outage creates an automatic personal refund.
Are the EX1550543 and MO1550821 incidents counted twice?
No. EX1550543 is the Exchange Online incident. MO1550821 is a broader Microsoft 365 advisory that describes potential impact to other services, and Microsoft’s partner guidance says advisory incidents are not typically eligible for SLA credits. Do not add the same Exchange Online impact twice. If another service such as Teams was separately affected, review that service’s own incident, SLA definition, and applicable fees.
Does the estimator use my entire Microsoft 365 invoice?
No. The amount estimate is only enabled when you confirm that the fee entered is the applicable fee for the affected Exchange Online service. Microsoft says credits apply to fees for the particular affected service. Bundled plans may require an allocation confirmed by Microsoft or your provider.
What if only Outlook desktop failed?
A desktop-only client problem may not meet the Exchange Online service-specific downtime definition. Compare the failure with the exact wording in the SLA version governing your subscription, preserve the tenant evidence, and ask Microsoft to confirm whether the failure mode is covered.
Do I submit the claim myself if I purchased through a CSP?
Contact the provider that invoices you. Microsoft’s Partner Center credit process allows eligible CSP direct and indirect providers to request service-outage credits from Microsoft. An indirect reseller cannot submit that Partner Center request directly as the provider.
Does Microsoft automatically issue service credits?
Do not assume a credit will be applied automatically. The published terms require a claim and supporting information, and Microsoft reviews whether a service credit is owed. Some CSP partners may coordinate or lodge claims for customers, so ask your provider what it is doing for this incident.
Is this tool an official Microsoft tool?
No. This is an independent Ultimate Info Guide estimator, not affiliated with or endorsed by Microsoft. It performs a transparent user-minute estimate and prepares a draft. It does not access your tenant, verify incident telemetry, submit a claim, or decide whether Microsoft owes a credit.
Related Ultimate Info Guide resources
Need to troubleshoot Outlook rather than prepare a business SLA request? Start with our Outlook not working guide. Looking for another interactive tool? Browse the Calculators and Pricing Tools hub.
Official references and further reading
Use the dated SLA and tenant-specific service-health details as the source of truth. Public news reports are context, not proof of your organization’s impact.
- Microsoft: Service Level Agreements for Online Services — official dated SLA documents and archive. The most recent English Worldwide edition as of November 13, 2026 is dated November 1, 2026.
- Microsoft Learn: How and when to request a credit from Microsoft — affected service rules, evidence and CSP submission process.
- Microsoft Learn: Check Microsoft 365 service health — where to find incident IDs and tenant-specific updates.
- Microsoft Learn: Get support for Microsoft 365 business — direct support route for eligible administrators.
- Microsoft 365 public service status — public status information.
- Ultimate Info Guide: Outlook not working troubleshooting guide — user-facing outage symptoms and Outlook troubleshooting.
- Ultimate Info Guide: Calculators and Pricing Tools — browse the site’s calculators and interactive tools.
