Of all the deadlines hanging over the Microsoft legacy estate, the nearest one belongs to Dynamics NAV 2017. Extended support ends in January, which gives any partner holding NAV clients roughly fifteen weeks to have a conversation they may have been deferring since spring.
It is a shorter runway than the one facing Dynamics GP, and it arrives with a decision attached. A Dynamics NAV upgrade to Business Central is not one route but two, and for a meaningful share of clients the obvious choice is the wrong one.
Where the versions stand
The last supported day for NAV 2017 is 11 January 2027. Microsoft's lifecycle table shows extended support expiring at 06:59:59 Pacific on 12 January, which amounts to the same thing.
NAV 2016 went out in April 2026, so those clients are already running unsupported software, whether or not anyone has told them. NAV 2018, the last release before the Business Central rebrand, runs to 11 January 2028. Mainstream support ended for every NAV version some years ago, the most recent being NAV 2018 in January 2023, so none of them have received anything but security patches for a while.
All NAV versions sit under the Fixed Lifecycle Policy, so these dates are fixed rather than rolling. Nothing stops working in January. What stops is the security patching, and with it any reasonable answer to an auditor asking how the finance system is maintained.
Upgrade or re-implement
This is the part that gets skipped.
A technical upgrade moves the existing database forward through successive versions until it lands in Business Central, carrying the client's configuration and history with it. It preserves what the business has built. It also inherits every decision made in that database since 2016.
A re-implementation starts with a clean Business Central environment and brings across the things the business actually needs: chart of accounts, customers, vendors, items, open balances, outstanding invoices. History stays available in the old system or in an archive, and the new environment is configured for how the business runs now rather than how it ran a decade ago.
Both are legitimate. The question is which one the client in front of you should be sold, and the honest answer depends almost entirely on what is in their customisations.
Where the cost sits
NAV customisations were written in C/AL. Business Central does not run C/AL, so anything custom has to be rebuilt as an extension. In most NAV migrations that rebuild is the single largest line in the budget, and it grows with every year the client has been on the platform.
The awkward part is that a lot of what gets rebuilt should not be. Fifteen years of accumulated modifications usually contain a number of things that exist because NAV could not do them natively in 2012 and Business Central now does natively in 2026. Rebuilding those faithfully means paying to recreate a workaround for a problem that no longer exists.
For a client with genuinely distinctive processes encoded in their system, the rebuild is worth it. For a client whose customisations are mostly old workarounds, layout tweaks and reports nobody runs any more, the rebuild costs more than the business it supports.
That second group is larger than most partners expect, and it is concentrated among exactly the smaller NAV clients who are hardest to serve profitably under a traditional upgrade project.
The case for a clean foundation
For those clients, a finance-first re-implementation is the better answer. They land on a current, supported, continuously updated Business Central environment, configured for the business as it operates today, without carrying forward a decade of decisions nobody remembers making.
It is also the route that can be delivered inside the runway they have left. A technical upgrade with a customisation rebuild attached is not a project that starts in October and finishes before January.
What this looks like on the platform
Qwyk is a Business Central onboarding and support platform built for Microsoft Partners, and NAV is now a live source system on it alongside Xero, Sage, QuickBooks and Dynamics GP.
The process is the same one that applies to any source. The platform connects to the client's system, extracts the data, maps it to Business Central with AI assistance and runs quality checks. On-premise NAV installations without an API are reached through a lightweight agent installed on the machine holding the data. Everything lands in a fully audited sandbox, and production is only written to when the partner reviews the sandbox and pushes it live, which is a single step.
You choose how involved to be on each client. Run the migration yourself through the partner portal, hand it to the client to self-serve through a guided wizard, or have Qwyk run it on your behalf. The client relationship stays with you in every case, and the client sees you rather than Qwyk.
For a partner with several NAV clients and one quarter to move them, the useful part is that the foundation stops being the thing that sets the timeline.
When an upgrade is still right
A re-implementation is not the answer for everyone, and pitching it as one would be a quick way to lose credibility with a client who knows their system.
Clients with deep, genuinely bespoke process logic in their NAV database need that logic rebuilt rather than discarded. Clients with regulatory or contractual reasons to keep transactional history in the live system need it carried across. Clients running heavy manufacturing or complex third-party integrations need scoping properly rather than automating.
Even then, the finance foundation can come across on the platform with the specialist work built on top of it, which is usually a faster and cheaper sequence than doing all of it by hand.
The point is to ask the question rather than defaulting to the upgrade because it is what NAV projects have always meant.
Where to start
Pull the list before you do anything else.
Which clients are on NAV, which version, and where each sits against the January and 2028 dates. Anyone still on NAV 2016 or earlier is already unsupported and should be at the top.
Then, for each one, ask what is actually in the customisations. Not how many there are, but how many still solve a problem Business Central cannot solve on its own. That answer sorts your list into the clients who need a project and the clients who need a clean start, and the second group is usually both larger and more urgent than it looks.
The GP deadline in 2029 gives partners time to plan. The NAV one does not, and January is fifteen weeks away.
Qwyk is a Business Central onboarding and support platform for Microsoft Partners. MSPs, systems accountants and BC consultants use Qwyk to migrate clients from Xero, QuickBooks, Sage, Dynamics GP and Dynamics NAV into Microsoft Dynamics 365 Business Central, automatically, in minutes. Partners choose how involved they want to be, and they always keep the client relationship.
Find out more on our page for BC consultants, our page for MSPs, our page for systems accountants, or the partner FAQ.