We’re using Nextcloud for most of our data storage and collaboration, and Microsoft 365 E3 for email and productivity. As we work toward compliance with the NCA’s Data Cybersecurity Controls, we’d like your help assessing: • What security capabilities in Nextcloud (e.g., access control, encryption, logging, watermarking, DLP) support DCC compliance? • Where Microsoft 365 E3 can help fill any gaps—especially for classification, watermarking, DLP, and audit/logging? • Any recommended Nextcloud apps or configurations that can accelerate compliance? We’re working under tight timelines, so a prioritized list of quick wins and a roadmap for deeper integrations would be very helpful.

To support NCA DCC compliance, Nextcloud offers key security features such as granular access control, end-to-end encryption, detailed logging/auditing, watermarking via apps like Nextcloud's Watermark app, and data loss prevention (DLP) capabilities through integrations or custom configurations. 

Microsoft 365 E3 complements these by providing robust classification tools (Sensitivity labels), advanced DLP policies, watermarking via Azure Information Protection, and comprehensive audit logs, helping fill gaps in data classification, watermarking, and monitoring. 

For quick wins, prioritize enabling Nextcloud’s encryption and access controls, deploying watermarking apps, and configuring basic logging; on the Microsoft side, enable classification labels, DLP policies, and audit logs. A roadmap for deeper compliance includes integrating both platforms for unified DLP and classification, automating watermarking at the document level, and deploying advanced analytics for continuous monitoring.

Have you considered that it is entirely possible to rely just on the Microsoft 365 E3 licenses, perhaps Microsoft E5 licensing (if deemed necessary) for your security and compliance needs? Many organizations (even in highly regulated sectors) take this all-in-one approach. I know Microsoft 365 enterprise licensing offers a rich set of security capabilities out-of-the-box that align with the NCA’s Data Cybersecurity Controls (DCC). If you configure and use these features fully, you can meet DCC requirements without needing a separate platform like Nextcloud. This approach offers comprehensive security in one platform and unified compliance management while likely simplifying and streamlining your GRC efforts. This would be our overall recommendation, though it may be considered bias as we are Microsoft partners.
I quickly developed a Prioritized Quick Wins and Integration Roadmap if you continue with your Nextcloud and Microsoft 365 E3 original approach. The immediate quick win actions are about hardening access and monitoring. It begins with MFA, audit logs, and a basic DLP policy. I hope that helps!