Is MS-900 Retired? Yes, and AB-900 Is What Replaced It

Yes. MS-900 is retired. Microsoft 365 Fundamentals (Exam MS-900) was retired on March 31, 2026, and you can no longer sit it. The exam that now stands in its place is AB-900: Microsoft 365 Copilot and Agent Administration Fundamentals. If you already hold MS-900 you keep it: Microsoft says earned fundamentals certifications stay on the Active Certifications section of your Microsoft Learn transcript and do not expire. What you cannot do is take the exam.

MS-900 did not retire alone. It went out in a wave of fundamentals retirements that most prep sites still have not caught up with.

Which Microsoft fundamentals exams retired, and when

All three dates have now passed. The MS-900 certification page carries a plain warning that reads "This certification is retired," and its study guide is stamped with the retirement date. That has not stopped a large chunk of the prep industry from still selling MS-900 courses and question banks, which is the practical reason this article exists.

What replaced MS-900?

AB-900, in practice. It is worth being precise about this, because most sites are not: Microsoft never printed the words "AB-900 replaces MS-900." What it did was retire MS-900 and, in the same announcement, promise a new fundamentals certification covering "core Microsoft 365 services, including Copilot and agents, while building their understanding of identity, security, and compliance essentials in Microsoft Entra and Microsoft Purview."

That description matches AB-900 line for line, and AB-900 is now the only Microsoft 365 fundamentals certification on offer. So the succession is real, but it is an inference from Microsoft's own words rather than a statement Microsoft made. Anyone telling you flatly that Microsoft announced a one-to-one swap is embellishing.

Is AB-900 just MS-900 with a new name?

No, and this is the part that will actually change how you study. We counted the verbs in the skills-measured section of both official study guides. The two outlines are nearly the same length (676 words for MS-900, 655 for AB-900), so the comparison is fair.

Fifty-four to zero. MS-900 asked you to describe things, from its first bullet to its last, and that is exactly how everyone taught it: flashcards, product names, a week of memorizing what SharePoint is for. AB-900 never asks you to describe anything. It asks you to identify objects, understand tasks, and perform, configure and monitor real administration. It is an administrator's exam wearing a fundamentals badge.

Two entire MS-900 domains no longer exist

MS-900 had four domains. AB-900 has three. The two that vanished did not get merged or trimmed, they were removed, and you can prove it by counting the words Microsoft uses in each outline.

That last row is the one that saves you the most time. AB-900 does not name Word, Excel, OneDrive or Viva even once. Every hour spent on an MS-900 course's "Microsoft 365 apps" module is an hour on content that has been deleted from the exam.

What is actually on AB-900

Three domains, and the weighting is not where anyone expects a fundamentals exam to put it:

• Understand data protection and governance tasks for Microsoft 365 and Copilot, 35 to 40%. The biggest domain. Sensitivity labels, classification, DLP, retention, and what Copilot is allowed to read. This is a Purview exam in disguise.
• Identify the core features and objects of Microsoft 365 services, 30 to 35%. The surviving piece of old MS-900, narrower and more concrete.
• Perform basic administrative tasks for Copilot and agents, 25 to 30%. Genuinely new. Licensing and assignment, readiness, deploying agents to a tenant.

Add the first and third together and 60 to 70 percent of AB-900 is governance plus hands-on Copilot administration. If a Copilot rollout is landing on your desk, that governance domain is the same work as the real thing: deciding which obligations apply to your tenant and mapping them to controls you can actually enforce before you switch the assistant on for 5,000 people. The exam has simply caught up with the job.

What should you do now?

One warning about the AB-900 fee. Microsoft does not list AB-900 in its published exam pricing feed, so nobody can honestly quote you a confirmed price for it. Every fundamentals exam that is in the feed (AZ-900, SC-900, DP-900) is $99 in the United States, so $99 is the sensible expectation. Confirm at checkout, and treat any site stating a firm AB-900 price as guessing.

The same goes for question counts. Microsoft publishes no question count for AB-900 and no pass rate for any of its exams. Its only general guidance is that most exams contain 40 to 60 questions. The passing score is 700 out of 1000, and Microsoft notes that because it is a scaled score, it may not equal 70 percent of the points.

How to prepare without a recycled question bank

AB-900 is new enough that most banks on sale are MS-900 content with the word "Copilot" pasted in. You can see the problem: a bank built on an outline that used "describe" 54 times cannot prepare you for an exam that uses it zero times. Recall questions will not get you through a governance domain.

The cleaner approach is to build your practice questions from current material, which means the AB-900 study guide itself, the Microsoft Learn modules, and your own admin-center notes. Upload them and generate AB-900 practice questions from your own Copilot administration notes, weighted to the three domains Microsoft actually publishes rather than the four that no longer exist.

If you are mapping out the whole fundamentals track, the other three are AZ-900, SC-900 and DP-900, all confirmed at $99 and all still live. And if the governance material is what interests you, the associate step up is SC-200, the security operations analyst exam and the only Microsoft exam whose outline names Security Copilot. For anything else, the certification exam generator takes any source document you have.