Outsourcing vs in-house: Who should build your CSSF SFDR JSON capability?

As Luxembourg-based asset managers face the mandatory requirement to submit SFDR Annex II and Annex V disclosures in JSON format to the CSSF, one operational question rises to the top:

Should you build this JSON reporting capability in-house or outsource it to a RegTech provider?

This article weighs the pros and cons of internal development vs third-party solutions, helping you make a strategic decision aligned with your firm’s regulatory risk appetite, data maturity, and resource capacity. 

What is required? 

To submit SFDR JSON to the CSSF, you need to: 

1. Map ESG disclosures to a structured schema (Annex II / Annex V) 
2. Generate a compliant machine-readable JSON file 
3. Validate against the CSSF’s technical schema 
4. Submit through the CSSF eDesk portal, alongside a PDF 

The complexity lies in the data structuring, transformation, validation, and maintenance of an evolving regulatory format. 
 
Option 1: Build In-House

Advantages 

Challenges 

• High setup cost: Requires investment in engineering, QA, and regulatory expertise 
• Schema maintenance: You must monitor and implement future changes to JSON formats 
• Validation risk: Errors in internal tools can result in rejections or compliance breaches 
• Limited scalability: Harder to scale quickly across hundreds of funds or jurisdictions 
   

Option 2: Use a RegTech vendor

Advantages 

Challenges 

• Vendor lock-in: You may rely on third-party technology and roadmap 
• Customisation limits: Some providers might be less flexible in integration with your internal ESG systems 
• Data security risks: ESG data must be shared externally 

Hybrid approaches are emerging

Some firms are adopting hybrid models, where: 

• A vendor generates the JSON, but 
• The middle office or compliance team retains control of validation, approval, and PDF/JSON alignment 

This allows for speed and compliance support without giving up internal data oversight.

Conclusion: Match the model to your maturity

There’s no one-size-fits-all answer. The decision between outsourcing and building in-house depends on your: 

• Volume of SFDR filings 
• Internal system readiness 
• ESG data control needs 
• Regulatory response agility 

For most asset managers, RegTech providers offer a quick and reliable route to SFDR JSON compliance — especially under tight timelines. However, firms with deep in-house capabilities may find long-term value in building an integrated, scalable solution that handles SFDR, CSRD, EET, and other regulatory formats under one roof. 

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