NAV and Business Central on-premises: two kinds of deadlines

The clock is ticking for Dynamics NAV and Business Central in different ways. Knowing which one is yours changes what it means to be ready.

Since Microsoft published new licensing dates for Dynamics NAV, GP, and SL at the end of July, it reads like a disturbing list of years. 2027. 2028. 2031. What you do is pick the one that applies to you and feel appropriately concerned.

The list is accurate but not very useful. It puts two different kinds of things in the same column.

There are fixed dates for Dynamics NAV, making it an obvious countdown. The dates are published years in advance. When the last one passes, the product line is finished. For Business Central on-premises, on the other hand, it feels more like a metronome. Two releases a year, around eighteen months of support each, and no final one.

For NAV, it’s a lease with an end date. For BC on-prem, it’s a rolling contract that renews on its own terms, whether you read the fine print or not. Neither of these scenarios is a crisis. What’s important here is that you would plan for them very differently. Most migration plans treat Business Central on-premises as if it also has a clear finish line.

The plan that does not stop the clock

Many NAV customers draw the same conclusion: they move to Business Central yet stay on-premises. It’s quite reasonable. Let’s say the organization doesn’t want to store sensitive customer data in the cloud and still relies on heavy customizations. On-prem feels more familiar, less disruptive. And yes, sometimes it is a viable option. Be it on-prem or cloud, we ask customers to move to the latest BC version.

If you do prefer an on-prem version, be clear about what it buys. The countdown ends, but the metronome starts. Instead of one large migration with a fixed date, you commit to endless smaller upgrades roughly every eighteen months. You drag your customizations along with you. And you regression-test every time.

You don’t cut costs this way. You amortize them. Upward. Every undocumented modification you bring along into your new ERP system gets retested at every cycle. Retested by people who were not there when it was written.

In certain cases, such a trade is genuinely worth it. But it must be done deliberately. Make sure you write the eighteen-month figure into the business case, not to discover it at the first upgrade.

December 2027: the closest deadline

There is one more deadline, and it arrives before all of the above.

Microsoft launched Bridge to Cloud 3 on 1 January 2026. It offers a 30% discount on most Dynamics 365 online products for eligible on-premises commercial customers, for a fixed period of three years, purchased through a partner. The signup window closes on 31 December 2027.

What does that mean in practice? During the migration, eligible customers can keep running their existing on-premises system alongside the new Dynamics 365 online subscription. They may also receive a 50% discount on additional on-premises users through 31 December 2027 (terms and limits apply). Paying for two ERP systems at once is what delays most migrations before they even start.

What to keep in mind: Microsoft can change or cancel a promotion at any time. It’s better to treat the specifics as something to confirm with your partner rather than something to build a budget on.

The discount can’t be the only reason to migrate. But if you do decide to migrate between now and 2031, moving during that window means a materially different cost for the same project.

The three years nobody talks about

Take a look at two of the NAV dates. Let’s say, NAV 2018. Security updates for the version stop on 11 January 2028. You can still renew licenses until 30 April 2031.

That leaves roughly three years and three months in which a company can be licensed but no longer get security patches.

For regulated industries, such a gap may become an audit finding, not a gray area. Auditors and insurers increasingly ask whether business-critical systems still receive vendor security updates, but being “licensed” does not imply that they do.

Organizations don't plan to run NAV in 2031. Yet here they are, paying the renewal, and one year turns into five.

You cannot plan backwards from the unknown

Every line in that table rests on something you cannot see: how much of your current solution you can actually carry into the new version.

That entirely depends on your current code. A decade or more of modifications, made by people who most certainly no longer work there, for reasons that most certainly were not written down.

For situations like that, we have Discovery X-ray. It’s a semi-automated review of your NAV or Business Central on-premises code that takes two days to identify critical vs nonessential modifications and map them to the functional area they affect. In addition to Discovery X-ray, we use AI to detect what functionality these changes were used for. Then, we discuss the findings with our customers. The review is secure as it reads code objects, not your data.

One more thing for those staying on-premises. The same review also answers the question that recurs every eighteen months. The code customizations that make each eighteen-month upgrade expensive are the same ones that would make a move to online expensive. All you have to do is find them once.

Discovery X-ray is a standalone package. You can use the Excel file with the Discovery X-ray modifications list to either migrate with us or as a second opinion – up to you.

Two kinds of deadlines and only one question

In fact, none of the deadlines or dates should drive your migration plan.

Basically, the question is not when Microsoft stops. The question is whether you rely on a countdown or a metronome, and how long your own move actually takes. Either way, the answers lie in the same place: knowing what’s inside the current system.

If you’d like to see what Discovery X-ray can highlight in your own solution, ask us for a sample report.