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One of the most important decisions during a Microsoft Dynamics 365 Finance & Operations (D365FO) implementation is whether to leverage the platform's standard capabilities or build custom extensions. While this may appear to be a technical choice, it has a direct impact on total cost of ownership (TCO), return on investment (ROI), implementation timelines, and the organisation's ability to scale and evolve in the future.
In practice, many organisations attempt to recreate processes from their legacy ERP solution. However, modern business applications such as Dynamics 365 Finance & Operations are built around industry best practices refined by thousands of organisations worldwide.
Before starting any development work, it is therefore worth asking a fundamental question: do you really need customisation, or can the requirement be addressed through configuration of standard D365FO functionality?
What is customisation in Dynamics 365 Finance & Operations?
In Dynamics 365 Finance & Operations, customisation refers to the development of additional functionality or extensions that go beyond the platform's out-of-the-box capabilities. It is typically considered when an organisation has unique business processes, regulatory requirements, or automation needs that cannot be effectively addressed through standard functionality.
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Why does the customisation decision affect ERP ROI?
Every custom development initiative carries costs beyond the initial build itself. Organisations should also consider:
- Additional testing and quality assurance
- Technical documentation
- Ongoing maintenance and support
- Validation during system updates
- Increased IT environment complexity
From a business perspective, customisation is an investment. Like any investment, it should generate measurable value. Well-designed extensions can:
- Automate time-consuming processes
- Reduce operational costs
- Minimise user errors
- Support competitive differentiation
- Address regulatory and audit requirements
Poorly justified customisations often increase costs without delivering meaningful business benefits.
When is it a good idea to use JUST the standard features of D365FO?
Staying with standard functionality is typically the best option when:
- The process does not provide a competitive advantage
- The requirement can be met through system configuration
- The organisation wants to minimise ERP maintenance costs
- Rapid deployment is a priority
- The functionality aligns with recognised industry best practices
Standard vs Customisation: A Comparison
| Criteria | Standard D365FO | Customised D365FO |
| Implementation cost | Typically lower | Typically higher |
| Implementation timeline | Shorter | Longer |
| System updates | Simpler | Require additional validation |
| Process fit | Based on best practices | Very high |
| Total Cost of Ownership (TCO) | Lower | Potentially higher |
| Flexibility | Limited to standard capabilities | Very high |
How does Microsoft recommend approaching D365FO customization?
For many years, Microsoft has promoted the “Configure First, Customize Second” approach. This approach aligns with the Extension Model used in Dynamics 365 Finance & Operations, which aims to minimize modifications to the application core and simplify the management of system updates. It means making the most of standard functionality, configurations, and available platform extensions before beginning any development work.
The reason is simple. Every additional customization increases the complexity of the environment, impacts maintenance costs, and requires additional validation during system updates. At the same time, leveraging standard functionality allows for faster solution deployment, easier adoption of new features provided by Microsoft, and a reduction in the total cost of ownership (TCO). This does not mean, however, that customizations are inadvisable.
Quite the contrary. Microsoft recommends creating extensions wherever they support unique business processes, regulatory requirements, or areas that provide the company with a competitive advantage. When well-designed, they allow Dynamics 365 Finance & Operations to be further tailored to the organization’s specific needs, enhancing the system’s usability and improving the user experience without sacrificing the benefits of the standard platform.
Expert recommendation
In most Dynamics 365 Finance & Operations implementation projects, the greatest business value comes from combining both approaches. Standard functionality should support processes common across the majority of organisations, while customisations should be reserved for areas where they improve operational efficiency, reflect unique business requirements, or support a distinctive operating model. The key principle is that every modification should deliver measurable business value and represent a conscious investment decision.
When is customisation justified?
If a process is unique to the organisation and forms part of its competitive differentiation, customisation may be justified.
Example: A manufacturer uses a proprietary production costing model that enables more competitive pricing than its competitors. Replicating this logic within D365FO could have a direct impact on profitability.
If standard features do not meet business or legal requirements, an extension may be necessary. Some organizations operate in highly regulated industries.
Examples of such requirements may include:
- financial reporting,
- auditing,
- compliance,
- tax requirements,
- document approval processes.
Well-designed automation can deliver rapid payback. If employees spend several hours each day performing repetitive tasks, automating those processes can often generate savings that exceed the implementation cost.
When is it better to avoid customization?
The standard features of Dynamics 365 Finance & Operations are usually the better choice when a requirement does not add new business value, can be implemented through system configuration, or pertains to a process commonly used in most organizations.
Reproducing legacy ERP processes should not be considered sufficient justification for custom development. If a change does not generate new business value but merely replicates user habits, it is worth considering adapting the process to the D365FO standard.
In many projects, it turns out that the biggest challenge is not the system’s technological limitations, but rather users’ habits from the previous solution.
Common mistakes in Dynamics 365 Finance & Operations projects
Some organisations focus on designing screens and functionality before defining their target business process. As a result, solutions are created that address individual user preferences rather than broader business objectives.
The first question should always be:
How should the process work?
Only then should the implementation approach be considered.
Development cost is only one part of the investment. Every customisation generates ongoing costs associated with testing, support, documentation, and future update validation.
From both a CFO and CIO perspective, understanding the lifetime cost of a solution is often far more important than focusing solely on implementation spend.
Why is this topic more important than five years ago?
Several market trends have increased the importance of making informed customisation decisions:
- more frequent SaaS updates,
- greater pressure on TCO,
- the rise of low-code,
- accelerated digital transformation initiatives
Organisations that evaluate customisations solely based on end-user requests frequently accumulate modifications with limited business value. By contrast, companies that involve process owners, finance teams, and IT stakeholders in decision-making are typically more successful in identifying investments that deliver measurable ROI.
Standard or custom? A checklist for CIOs and CFOs
✅ When should you stay with standard D365FO functionality?
If the answer is "yes" to most of the following questions, standard functionality will likely be the right choice:
- Is the process common across most organisations in the industry?
- Can the requirement be addressed through configuration?
- Does the functionality fail to provide competitive advantage?
- Is rapid deployment a priority?
- Does the organisation want to reduce maintenance and regression testing costs?
- Are frequent system updates planned?
- Can the process be aligned with best practices supported by D365FO?
✅ When should you consider customisation?
If the answer is "yes" to most of these questions, a custom extension may be worth evaluating:
- Does the process directly affect revenue or profit margins?
- Does the solution support competitive advantage?
- Are there regulatory, tax, or audit requirements not covered by standard functionality?
- Does the current process generate significant operational costs?
- Will automation reduce workload or user errors?
- Do the expected benefits outweigh development and maintenance costs?
- Will the solution still be needed in three to five years?
✅ Questions every CFO should ask
- What is the total cost of ownership?
- Will the customisation generate measurable ROI?
- How will it affect future maintenance costs?
- Can the same business outcome be achieved at a lower cost?
- What financial risks are associated with maintaining a bespoke solution?
✅ Questions every CIO should ask
- How will the customisation affect the solution architecture?
- Will it increase system complexity?
- What impact will it have on Microsoft updates?
- Does the organisation have the expertise to maintain it?
- Is it aligned with the long-term IT and digital transformation strategy?
The hidden costs of customisation
When evaluating a custom solution, organisations frequently consider only development costs. This is a mistake. The true cost also includes:
Development costs
- Requirements analysis
- Solution design
- Development
- Testing
Maintenance costs
- User support
- Issue resolution
- Ongoing enhancements
Upgrade costs
Each future system update requires validation that the extension continues to function as expected.
Knowledge dependency risk
Over time, organisations become dependent on the individuals who understand how the custom solution works.
For this reason, the real question is not"How much will it cost to build?" but rather"What will it cost to own over the coming years?"
A four-question framework before approving development
Clearly define:
- Which process requires change
- Who is affected
- What benefits are expected
- Whether the solution reduces costs, lowers risk, increases revenue, or accelerates execution.
Before committing to development, evaluate:
- Standard configuration options
- Existing D365FO capabilities
- Low-code solutions
- Available integrations
Often, the requirement can be addressed more quickly and cost-effectively without writing new code.
The assessment should include:
- Development
- Testing
- Documentation
- Maintenance
- Future upgrades
A well-designed adaptation should support long-term business growth, not simply solve a temporary problem.
Standard vs Custom: Practical Examples
Example 1
During one project, users insisted on replicating the interface of a legacy ERP system.
Process analysis revealed that standard D365FO configuration achieved exactly the same business outcome without any additional development.
Result
- no development costs,
- faster implementation,
- simpler upgrades and updates.
Example 2
A manufacturing company used its own proprietary model for tool cost planning and production settlement.
Analysis confirmed that the process represented a significant source of competitive advantage.
Result
- a dedicated extension was implemented,
- the unique business model was preserved,
- process automation increased substantially.
FAQ
No.
In many situations, standard D365FO functionality fully satisfies business requirements.
Customisation is typically justified only when the organisation has unique business processes or specific regulatory obligations.
The best approach is to evaluate its impact on:
- revenue,
- costs,
- operational risk,
- competitive advantage.
They can increase testing and validation effort during updates.
For this reason, every customisation should have a clear business justification and be designed according to Microsoft's recommended extension practices.
Conclusion
The most effective organisations do not begin by asking: "What can we build?"
Instead, they start with: "What business problem are we trying to solve?"
This approach enables organisations to maximise the value of standard Dynamics 365 Finance & Operations functionality, reduce long-term maintenance costs and focus development investments on areas that deliver genuine business value.
At RSM Poland, we help organisations evaluate both the process and technology dimensions of ERP implementations. As a result, the "standard vs custom" decision becomes a strategic business choice rather than a purely technical one.
In most Dynamics 365 Finance & Operations projects, the best outcomes are achieved by maximising standard functionality while applying customisations selectively in areas that generate measurable business value.
Planning a Dynamics 365 Finance & Operations Implementation or Reviewing Your Customisation Strategy? Contact the RSM experts.
We can help you assess which requirements should be addressed through standard functionality and which genuinely justify investment in dedicated extensions.
