What carries across from AX and NAV
Most of what you know still applies. The ledger, posting logic, inventory, purchasing and production flows are recognizable descendants of what you configured in AX 2012 or NAV. Microsoft notes that AX 2012 already had extension features such as pre and post events, and that these kept growing as the new application developed. If you used them, you have a head start. Your real advantage is knowing how legacy customers set up their systems, because that is what every upgrade has to untangle.
On the NAV side, the Business Central base application is a direct descendant of NAV. Microsoft's upgrade path runs from NAV 2015 through NAV 2018 via Business Central version 14. A consultant who knows why a client built a custom table in 2016 can explain to the project what has to happen to it now. That history is useful to the project as long as you pair it with current tooling.
What has changed: extensions, AL and the cloud
In Finance, Supply Chain Management and Commerce, Microsoft says extensibility is now the only customization framework and overlayering is not supported. The reason is the cloud. Frequent servicing needs customizations that do not break when Microsoft updates the base code. Moving old overlayered code to extensions can be a big job, and some customizations have to be redesigned from scratch. Those projects need people who can read the old code and rebuild it the new way.
For NAV, the change is the language. Business Central 2019 release wave 2 (version 15) replaced C/AL with AL, and C/SIDE was deprecated. The base application now ships as an AL extension, and you develop in Visual Studio Code. A NAV customer moving to Business Central online has to convert every C/AL customization into AL extensions. The alternative is a reimplementation that brings across only master data, balances and some history.
Lifecycle Services and release waves
Finance and operations projects have historically been run through Lifecycle Services (LCS), Microsoft's collaboration portal for managing the application lifecycle. It covers projects, methodologies, the business process modeler, cloud-hosted environments, upgrade analysis and issue search. Microsoft says some LCS features have been deprecated as part of its One Dynamics One Platform work, so learn the current tooling as well as the old portal.
Release waves set a new rhythm. Business Central online gets major updates twice a year, in April and October, plus monthly minor updates. On-premises upgrades every few years are over. Your customizations, tests and training materials have to keep pace with Microsoft's schedule, and that ongoing work is a large part of the job now.
The market for legacy skills and pay
Legacy knowledge pays when you combine it with current skills. Every NAV customer still on C/AL and every AX customer still overlayered needs an upgrade or a reimplementation, and those projects want people who understand both ends. If you only know the old system, you limit yourself to support work that will shrink as customers migrate. I have no reliable pay data specific to AX, so this guide gives none.
US adverts on D365 Market that state pay for Dynamics 365 roles show a median of $153,050 a year. In the UK, IT Jobs Watch adverts citing Dynamics 365 show a median permanent salary of £65,000 and a median contract rate of £509 a day for the six months to 5 November 2026. All of these figures are advertised pay. They are not earnings and they are not official rates.
Pay
USD a year, before tax. Source: D365 Market advertised pay, US adverts that state pay, snapshot 2026-11-05 (48 adverts, 34 employers). This is advertised pay, not earnings, and it leans toward states with pay transparency laws. No AX-specific figure is given because the data is too thin. Refer to the Dynamics 365 (General) salary guide for figures from live adverts.
What you need
- Extension-based developmentFinance and operations apps support extensions only. You need to know how to rebuild overlayered logic as extensions.
- AL and Visual Studio CodeBusiness Central development is AL-only and runs in Visual Studio Code. You also need to know how C/AL customizations convert to AL.
- X++ for finance and operationsFinance and operations developers still write business logic in X++, and MB-500 tests it.
- Release wave disciplinePlan testing and regression work around the April and October major updates and the monthly minor updates.
- A current certificationMB-310, MB-330 or MB-500 for AX backgrounds and MB-820 for NAV developers. Associate certifications expire each year and renew through a free online assessment on Microsoft Learn.
How to get there
- Month 1Pick your target productFrom AX, aim for Finance or Supply Chain Management. From NAV, aim for Business Central. Stay with the business processes you already know.
- Months 1-3Rebuild your toolsetAX developers should practice extensions in X++. NAV developers should set up Visual Studio Code and write AL extensions. Functional people should learn the current setup screens and the LCS tooling.
- Months 2-4Take one associate examMB-310 or MB-330 for functional AX people, MB-500 for AX developers, MB-820 for NAV developers. A score of 700 passes.
- Months 4-12Work on an upgrade projectJoin an overlayering-to-extensions migration or a C/AL-to-AL conversion. These projects make the most use of your legacy knowledge.
- OngoingKeep current every waveRenew your certification each year and read the release plans before each April and October update.
Open now on D365 Market
Questions people ask
Can I still customize Dynamics 365 the way I did in AX 2012?
No. Microsoft says extensibility is the only customization framework in Finance, Supply Chain Management and Commerce, and overlayering is not supported. You write extensions against the base application and leave its code untouched.
Is C/AL still used in Business Central?
No. Business Central 2019 release wave 2 (version 15) replaced C/AL with AL, and the C/SIDE development environment was deprecated. Old C/AL customizations have to be converted to AL extensions before a customer can move to Business Central online.
Do NAV customers have to convert all their code to move online?
Not always. A full migration requires converting C/AL customizations to AL extensions. A reimplementation brings across only essential data such as master data, balances and some posted history, and it does not require extension conversion.
Which certification should a former AX developer take?
MB-500, the Dynamics 365: Finance and Operations Apps Developer Associate. It covers X++ development in the current product, and it is one of the associate certifications that count toward the AB-100 architect expert certification.
How often does Business Central change now?
Major updates arrive twice a year, in April and October, and minor updates roll out every month. Business Central online follows the Microsoft Modern Lifecycle Policy, which means continuous service updates.
Sources
- Microsoft Learn: Extensibility home page, finance and operations
- Microsoft Learn: Migrate from overlayering to extensions
- Microsoft Learn: Migrate Dynamics NAV to Business Central online
- Microsoft Learn: Upgrading to Business Central 2026 release wave 2
- Microsoft Learn: Lifecycle Services resources
- Microsoft Learn: Service overview for Business Central online
- Microsoft Learn: Agentic AI Business Solutions Architect Expert
- D365 Market: advertised salaries
- IT Jobs Watch: Dynamics 365 permanent salaries, UK
- IT Jobs Watch: Dynamics 365 contract rates, UK
