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# Developing COM Add-ins with Phillip Stiefel
- URL: https://nolongerset.com/aug-com-add-ins-stiefel/
- Published: 2025-01-19T15:54:28.000Z
- Updated: 2026-05-08T12:43:34.000Z
- Description: How to Extend Access's Development Environment with Custom COM Add-ins (an Access User Group talk with Philipp Stiefel)
- Author: Mike Wolfe
- Tags: AUG Video Recap, #Import 2026-05-20 02:59

Want to extend Access's development environment with powerful custom tools? COM add-ins might be just what you need.

In this Access Europe presentation, former MVP Philipp Stiefel demonstrates how to create COM add-ins for Microsoft Access using modern development tools. Drawing from his experience building commercial add-ins like Ivercy and Find & Replace, Philipp walks through the fundamentals of COM interfaces, implementation patterns, and best practices for add-in development.

Whether you're looking to enhance your development workflow or create tools for other Access developers, this comprehensive overview provides practical insights into building professional COM add-ins.

## Why Use COM Add-ins?

### Key Benefits

- Enhance the Access development environment with custom tools
- Leverage powerful programming environments beyond VBA
- Seamlessly integrate into the Access UI
- Optionally extend functionality to other Office applications
- Access APIs not available through standard VBA declarations

### Primary Use Cases

- Developer productivity tools
- Enhanced development environment features
- Cross-Office application integration
- Complex functionality requiring compiled code

## Technical Foundation

### COM Basics

- Binary interface standard built into Windows
- Programming language independent
- Foundation for Office object libraries
- Requires compiled objects (DLLs/EXEs)
- Cannot be implemented directly in VBA

### Required Interfaces

- IDTExtensibility2 - Core add-in interface
- IRibbonExtensibility - Optional ribbon support
- Custom interfaces for specific functionality

## Implementation Details

### Essential Methods

- OnConnection - Called when add-in loads
- OnDisconnection - Called during shutdown
- OnStartupComplete - After host app initializes
- GetCustomUI - Returns ribbon XML (if implementing ribbon)

### Registration Requirements

- COM class registration in Windows Registry
- Add-in registration in Office application
- Can be per-user (HKCU) or machine-wide (HKLM)
- Registration scripts simplify deployment

## Development Best Practices

### Environment Setup

- Use modern development tools (Visual Studio, TwinBASIC)
- Reference required type libraries
- Consider late binding for Office automation
- Implement proper debugging support

### Design Considerations

- Plan for both 32-bit and 64-bit compatibility
- Handle loading/unloading gracefully
- Implement proper error handling
- Consider cross-Office compatibility if needed

## Debugging and Testing

### Key Tips

- Use "Attach to Process" for live debugging
- Add diagnostic message boxes during development
- Test with other add-ins disabled
- Verify registration settings

## Conclusion

COM add-ins provide a powerful way to extend Access's development environment beyond what's possible with traditional Access add-ins. While the initial setup requires more technical knowledge than VBA-based solutions, the benefits of compiled code, advanced APIs, and cross-Office compatibility make them invaluable for serious Access developers.

## Recording

The full recording is available on [YouTube](https://www.youtube.com/watch?v=kisZ7CbBSXk):

## Join Live!

Want to get even more out of these presentations? Join the live Access User Group events! The next upcoming events are listed on the [AUG Event Calendar](https://accessusergroups.org/calendar/?ref=nolongerset.com).

Attending live gives you the opportunity to:

- Interact directly with presenters during Q&A sessions
- Network with other Access developers
- Share your own experiences and challenges
- Get immediate answers to your specific questions
- Participate in group discussions

With multiple user groups across different time zones (and languages!), you're sure to find a meeting time that works for your schedule.

## See Also

[Building COM Add-ins with Geoffrey L. GriffithBuilding Office COM Add-ins with Visual Studio Tools: Part Two of a Two-Part Deep Dive (an Access Pacific user group talk with Crystal Long and Geoffrey L. Griffith)![](https://nolongerset.com/content/images/size/w256h256/2020/09/NLS_Icon_square.png)No Longer SetMike Wolfe![](https://nolongerset.com/content/images/2024/12/AUG-Building-COM-Add-ins.jpg)](https://nolongerset.com/aug-com-add-ins/)

[Making Access Add-ins with Crystal LongCreating Add-ins for Microsoft Access: Part One of a Two-Part Deep Dive (an Access Pacific user group talk with Crystal Long and Geoffrey L. Griffith)![](https://nolongerset.com/content/images/size/w256h256/2020/09/NLS_Icon_square.png)No Longer SetMike Wolfe![](https://nolongerset.com/content/images/2024/12/AUG-Making-Access-Add-ins.jpg)](https://nolongerset.com/aug-access-add-ins/)

### Acknowledgements

- *Base cover image generated by FLUX-schnell*
- *Initial draft generated by Claude-3.5-Sonnet*