How to Handle Custom Development in Implementation: A Guide for Dynamics 365 Projects
When implementing a business solution like Microsoft Dynamics 365, the goal is clear to improve operations, streamline workflows, and support long-term growth. But in the real world, businesses are rarely “out of the box.” Most have unique processes, industry-specific needs, and legacy systems that require a custom touch.
That’s where custom development comes into the picture.
Handling custom development in any software project is challenging, and this is especially true during a Dynamics 365 implementation. Whether you're customizing finance modules, modifying supply chain workflows, or building integrations with third-party platforms, the process needs to be planned carefully to avoid delays, scope creep, or unstable solutions.
In this article, we’ll walk through how to approach custom development within a Dynamics 365 implementation from initial planning to long-term support.
Start with a Deep Discovery Phase
Before writing a single line of code, it's critical to understand what your business really needs. This means sitting down with stakeholders across departments to identify:
What processes cannot be met with standard Dynamics 365 features
Which customizations are absolutely necessary for daily operations
What goals the business hopes to achieve post-implementation
Documenting use cases, user stories, and exceptions is the foundation for making smart customization decisions.
It’s also helpful to challenge assumptions. In some cases, a process that feels “unique” may actually be addressed with native Dynamics 365 capabilities. Unnecessary customization adds risk and complexity, so always explore built-in solutions first.
Define What Needs to Be Customized
Not every problem requires development. Sometimes, configuration is enough. In Dynamics 365, configuration involves adjusting existing settings, workflows, or fields. Custom development, on the other hand, involves coding new functionality.
Here are common areas that require custom work during a Dynamics 365 implementation:
Custom APIs to connect with external systems
Extensions to standard forms and entities
Automated workflows that do not exist out of the box
Industry-specific logic (e.g., compliance rules, billing models)
Role-based dashboards and reporting tools
Once you know what needs to be built, document it clearly. Use functional and technical design documents to align business users with developers before moving forward.
Follow Microsoft’s Best Practices for Extensibility
Dynamics 365 is part of the larger Microsoft ecosystem, which means it follows a structured development model. The best way to handle custom development is to follow Microsoft's recommended approach: extension-based customization rather than overlayering core code.
Extensions allow you to add or change behavior without modifying the base system. This makes upgrades easier, reduces risk, and keeps your environment more stable over time.
Your developers should use tools like:
Visual Studio with Lifecycle Services (LCS)
Azure DevOps for version control and CI/CD pipelines
Power Platform for low-code extensions
Dataverse for scalable data storage
Keeping your code clean and modular will pay off during upgrades, audits, and future development efforts.
Build, Test, and Test Again
After development begins, quality control is essential. Every customization should go through:
Unit testing by the developer
Functional testing by key users
Integration testing to confirm everything works together
UAT (User Acceptance Testing) before deployment
Use sandbox environments that match your production setup as closely as possible. Testing should not only check for functionality but also performance and scalability.
Remember, the smallest bug in a financial report or supply chain workflow can lead to serious downstream issues.
Plan for Ongoing Support and Documentation
Custom development doesn’t stop at go-live. You’ll need a support plan to monitor and maintain your custom code. This includes:
Version control and rollback plans
Documentation for each customization
A clear escalation path for issues
Additionally, keep an eye on system updates from Microsoft. New releases may introduce features that replace your custom work or require updates to your codebase.
Custom development can take your Dynamics 365 implementation from good to great, but only if it’s handled strategically. By starting with careful discovery, following best practices, and ensuring solid testing and support, you can develop the custom features your team needs without sacrificing stability or scalability.
In short, successful customization is not about writing more code. It’s about writing the right code for the right reasons, at the right time.