Quick answer
MB-820 (Microsoft Certified: Dynamics 365 Business Central Developer Associate) tests whether you can build, extend, debug, and integrate AL extensions for Business Central — not configure the app. One domain, Develop by Using AL Objects, carries 35-40% of the exam by itself, more than the next two domains combined. If you already write AL professionally, focus your remaining study time on the two smaller domains most developers skip: development tools (test codeunits, telemetry) and API integration (REST, OData). Everything below traces to Microsoft's official MB-820 study guide, checked 2026-09-07.
MB-820 is Microsoft's associate-level certification for Dynamics 365 Business Central developers — the exam behind the Microsoft Certified: Dynamics 365 Business Central Developer Associate credential. It replaced nothing directly; it's the dedicated developer-track exam that sits alongside MB-800 (the functional-consultant exam for the same product). This guide walks through what MB-820 actually measures, clears up the mix-ups candidates run into before booking, and folds a study plan into that process rather than bolting one on at the end.
What Does the MB-820 Exam Actually Test?
Microsoft's audience profile for MB-820 is explicit: a Business Central developer designs, develops, tests, and maintains solutions based on Business Central, building apps that extend the base product, integrating it with other applications like Power Platform, and keeping data current through upgrades. That's six named skill areas, each with its own weight:
Describe Business Central
10-15%
Install, develop, and deploy
10-15%
Develop by using AL objects
35-40%
Develop by using AL
15-20%
Work with development tools
10-15%
Integrate with other applications
10-15%
Notice what's missing: no domain called "configuration," no posting groups, no dimensions. Every domain assumes you're writing code in Visual Studio Code with the AL Language extension, not clicking through the Business Central UI. That distinction is the single most common source of confusion for candidates evaluating MB-820, which is the myth worth clearing up first.
Isn't MB-820 Just the Developer Version of MB-800?
Not in any way that overlaps on the exam. MB-800(Business Central Functional Consultant) tests configuring the product for a business: setting up companies, posting groups, dimensions, workflows, and processing purchase and sales documents inside the standard UI. MB-820 tests building the product's extensions: tables, pages, reports, codeunits, XMLports, queries, and interfaces written in AL. A functional consultant configures what a developer built. Reading "Business Central" in both exam names is where the similarity ends — the skills-measured lists share almost no line items.
If your job title is "Business Central developer" and you spend your day in Visual Studio Code rather than the web client's Assisted Setup guides, MB-820 is the correct exam. If you spend your day configuring modules for end users, MB-800 is the one you want — going after the wrong exam is the most expensive mistake a candidate can make here, since the study material genuinely doesn't transfer.
Study plan note: If you've read an MB-800 study guideand found it easy to follow, that's not a signal you're ready for MB-820 — it's a signal you understand a different job. Start MB-820 prep from the AL language documentation, not from Business Central's admin UI.
Do You Need C#, .NET, or X++ Experience to Pass MB-820?
No — and conflating them is a second common mix-up, usually with MB-500 (Finance and Operations Apps Developer), which does test X++ against the Application Object Tree. MB-820 tests AL, a separate language purpose-built for Business Central extensions. AL borrows syntax conventions from Pascal-style languages more than from C#, and its extension model is event-driven (publisher/subscriber events and object extensions like tableextension and pageextension) rather than the classic-object-oriented inheritance patterns .NET developers default to.
That said, general programming fundamentals transfer directly: variables, data types, control flow, error handling, and access modifiers are all named objectives under "Develop by using AL," and anyone comfortable with a C-family or Pascal-family language picks up AL's syntax quickly. What doesn't transfer is assuming Business Central's extension model works like a typical OOP inheritance model — study the events-and-triggers objective specifically, since it's where AL diverges most from general-purpose languages.
Why "Develop by Using AL Objects" Decides Whether You Pass
At 35-40%, this single domain outweighs the two smallest domains combined and is roughly triple the size of "Describe Business Central." It covers building and extending tables, pages (including Role Centers), reports, enums, XMLports, codeunits, permission sets, and queries — essentially every object type an AL extension is assembled from. Underinvesting here is the single biggest reason otherwise-competent developers fail MB-820.
A weighted study allocation makes the imbalance concrete. If you have roughly 40 hours of prep time available:
| Domain | Exam weight | Suggested hours (of 40) |
|---|---|---|
| Develop by using AL objects | 35-40% | 15 hours |
| Develop by using AL | 15-20% | 7 hours |
| Install, develop, and deploy | 10-15% | 5 hours |
| Work with development tools | 10-15% | 5 hours |
| Integrate with other applications | 10-15% | 5 hours |
| Describe Business Central | 10-15% | 3 hours |
Inside the objects domain, prioritize by how often each object type shows up in real extension work: tables and table extensions first (nearly every extension touches one), then pages and page extensions, then codeunits with event subscribers, and only then reports, queries, and XMLports — which are individually smaller but still each carry their own named sub-objective, so don't skip them entirely.
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Start Free Practice →Is the Development Tools Domain Safe to Skip?
No, and it's the domain candidates most often deprioritize because it doesn't sound like "real" AL development. "Work with development tools" (10-15%) covers two named sub-objectives: implementing semi-automated test processes with the Test Toolkit and writing test codeunits, and managing and analyzing telemetry — including configuring telemetry and creating custom telemetry signals.
Both are underrepresented in most self-study material because they're operational skills rather than syntax skills — you can't learn them by reading AL code samples, only by actually running the Test Toolkit against a codeunit or wiring up Application Insights telemetry. Budget hands-on time here specifically; passive reading won't cover it the way it can for object syntax.
Will Free Microsoft Learn Modules Get You to a Passing Score?
For the syntax and object-model objectives, largely yes — Microsoft's AL documentation and the linked Business Central developer landing page cover the language thoroughly and are free. Where free material runs thin is exactly where the exam gets scenario-based: recognizing which object type or event pattern a described business requirement calls for, under exam time pressure, rather than reading a reference page with the answer already labeled.
| Resource | Best for | Gap |
|---|---|---|
| Microsoft Learn (self-paced) | Free, aligned to exam objectives, good for syntax | Few scenario-style questions under time pressure |
| Instructor-led course (MB-820T00-A) | Structured 5-day pace, live Q&A | Paid; less useful if you already write AL daily |
| AL documentation (reference) | Precise syntax and API detail | Not organized by exam domain |
| Scenario-based practice questions | Closing the "which object/event fits this requirement" gap | Not a substitute for reading the language docs first |
Work through the AL documentation domain by domain first, then use scenario-based MB-820 practice questions to check whether you can apply what you read under exam-style constraints, not just recognize it on a reference page.
Not sure where your gaps are?
Take the free MB-820 readiness quiz. No signup required. Get a sense of which of the six domains needs the most work before you commit study hours.
Check My ReadinessMB-820 FAQ
What is MB-820?
MB-820 is the exam for the Microsoft Certified: Dynamics 365 Business Central Developer Associate credential. It validates the ability to design, develop, test, and maintain Business Central extensions using AL, Visual Studio Code, and the platform's APIs, per Microsoft's official certification page (checked 2026-09-07).
What are the prerequisites for MB-820?
Microsoft does not enforce a prerequisite exam. Its audience profile assumes applied knowledge of AL, the Business Central development environment, and ALM practices including source control and CI/CD — none of which is checked at registration, only tested on the exam itself.
How much does MB-820 cost and how long does it take?
MB-820's own page doesn't publish a price, duration, or question count. Per Microsoft's general exam FAQ (checked 2026-09-07), Associate exams typically cost US$165, and per its general Exam Duration policy, associate exams without labs run about 100 minutes (120 minutes seat time) with typically 40-60 questions. Confirm your exact figures at registration.
Does MB-820 expire?
Yes, after 12 months, per Microsoft's standard associate-certification renewal policy. Renewal is a free online assessment on Microsoft Learn, not a repeat of the full proctored exam.
What comes after MB-820?
There's no official next exam in a linear path. Developers commonly pair MB-820 with PL-400 (Power Platform Developer) if they build Power Platform integrations against Business Central, or move toward architecture-focused roles once they've shipped several AppSource-published extensions.
About MSCertQuiz
MSCertQuiz sells a scenario-based MB-820 practice bank and a free readiness quiz; this guide was written by the same team that builds and maintains that question bank, grounded against Microsoft's official MB-820 study guide rather than recycled AL tutorials. Start with free practice questions before deciding whether the full bank is worth it.