The Luxembourg Commission de Surveillance du Secteur Financier has published a communiqué and Circular CSSF 25/900 updating the annual reporting framework for undertakings for collective investment administrators (UCIAs) under Circular CSSF 22/811, with changes taking effect from 31 December 2025. The revised framework introduces a new self-assessment questionnaire focused on key requirements of the UCIA Circular and significantly reduces the information to be reported on UCIAs’ business activities and resources. UCIAs whose financial year ends on or after 31 December 2025 must use the revised reporting approach. For credit institutions, investment fund managers, support professionals of the financial sector and certain investment firms acting as UCIAs, the UCIA reporting is integrated into annual long form reports or SAQs under Circulars CSSF 22/821, 23/839, 24/850 and 25/870, removing the need for separate UCIA reporting. Specialised professionals of the financial sector acting as UCIAs will report via the annual Specialised PFS SAQs on CSSF eDesk, with a submission deadline of three months from the effective date, while other UCIAs will continue to use the UCI Administrator Reporting Tool on eDesk (with optional API submission via the S3 protocol) and retain a deadline of five months after the UCIA’s financial year-end starting from the effective date. Circular CSSF 25/900 applies from 31 December 2025, repeals Annex B of Circular CSSF 22/811, and removes the single deadline reference given the new entity-specific timelines. The UCIA Circular is also amended to reflect the entry into application of the Digital Operational Resilience Act in January 2025, and the CSSF indicates that modalities and submission instructions, including user guides where relevant, will be made available on its website.