It is one of the first questions businesses ask when they start thinking seriously about moving from Dynamics NAV to Business Central: how long is this actually going to take? The honest answer is that it depends — but not in a vague way. There are specific factors that drive project length, and understanding them allows you to form a realistic expectation of your own timeline before any consultancy engagement begins.
The Short Answer: Three to Nine Months
For most businesses upgrading from a supported version of Dynamics NAV to Microsoft Dynamics 365 Business Central, the project timeline from kick-off to go-live falls somewhere between three and nine months.
Three months is achievable for smaller businesses with clean data, limited customisations, and straightforward processes. Nine months or more reflects complex environments — heavily customised NAV systems, multiple external integrations, manufacturing or distribution operations with bespoke functionality, or large data sets requiring significant preparation work.
The Factors That Drive Timeline
The Version of NAV You Are Upgrading From
The older your NAV version, the larger the technical gap between your current system and Business Central. A business on NAV 2018 is upgrading across a smaller gap than a business on NAV 2013. Microsoft released more mature migration tooling specifically for NAV 2018, and the data structures are closer to Business Central than earlier versions.
The Extent of Customisation
NAV customisations were built in C/AL, a proprietary development language. Business Central uses AL extensions. The amount of custom development in your current NAV environment is probably the single biggest driver of project length. A partner with deep NAV knowledge can identify quickly which customisations are essential and which were workarounds for problems that Business Central now solves natively — this kind of informed assessment can significantly reduce rebuild scope.
Data Quality and Volume
Data migration is consistently the phase that takes longer than anticipated. Businesses with clean, well-maintained master data move through this phase faster. Businesses with years of accumulated data quality issues — duplicate records, inconsistent coding, partial information — need to spend time cleaning data before migration can begin.
Number and Complexity of Integrations
Almost every NAV environment has external integrations — payroll, CRM, ecommerce, EDI, warehouse management. Each integration that needs to be rebuilt or reconfigured for Business Central adds time to the project. Understanding the integration landscape before the project starts is important for accurate timeline planning.
Business Complexity
Manufacturing businesses, distributors, and businesses with multiple legal entities consistently take longer to migrate. Supply chain operations with multiple warehouses, complex stock management, or EDI requirements add similar complexity.
Client-Side Resource Availability
This is perhaps the most underestimated factor. A NAV to Business Central migration requires significant time investment from the finance director who owns the project, the system administrator who knows the current environment, and the end users who participate in testing and training. Projects where client-side resource is genuinely available tend to run faster.
Project Phases and Typical Time Allocations
A well-run NAV to Business Central upgrade follows a structured delivery methodology. Here is how the phases typically break down for a mid-complexity project:
What Causes Projects to Run Over
The most common causes of timeline overruns are data quality issues discovered late, scope changes introduced mid-project, integration complexity that was underestimated at scoping, and insufficient client-side resource during testing and training.
Most of these are avoidable with a thorough discovery phase and honest scoping at the start. Choosing an experienced partner — one who has upgraded environments similar to yours and knows where the risks tend to be — significantly reduces the likelihood of timeline surprises. Our guide on choosing a Business Central implementation partner covers what to look for in detail.
What You Can Do to Accelerate Your Project
The most effective things a business can do to reduce project length are within their control before the project even starts:
- Clean your master data now — remove duplicate customers, suppliers, and items; update contact information; rationalise your item list.
- Document your current customisations — understand what has been built, why it was built, and whether you still need it.
- Map your current integrations — know which external systems connect to NAV, how they connect, and whether the connections are still required.
- Identify your project team now — name the people who will own the data migration, participate in testing, and receive training. Confirm their availability.
- Decide on your historical data policy — determine how much historical data you need in Business Central and what you are comfortable archiving.
Getting a Timeline Specific to Your Environment
Generic timelines are useful for planning conversations, but the timeline for your project depends on your specific environment. The only way to get an accurate estimate is for an experienced partner to assess your current NAV system — the customisations, the data, the integrations, and the business processes — and produce a scoped project plan based on what they actually find.
NetMonkeys has delivered NAV upgrades from every version from 2009 to 2018. Our discovery process is designed to surface scope accurately at the start, so project timelines and costs are predictable.
We'll assess your NAV system and give you a realistic, scoped estimate — not a generic range pulled from thin air.
