CSSF Reporting for UCIs: The Complete List of Obligations
A Luxembourg undertaking for collective investment owes the CSSF twelve distinct reporting obligations, spread across five frequencies and six transmission channels. This page lists every one of them — what it contains, when it is due, in which format, and under which circular.
It follows the CSSF page Reporting to be submitted by UCIs, last updated 26 May 2026. Where the CSSF updates a circular, the authority’s page prevails over this summary.
12
Reporting obligations across all UCI types
10
Calendar days to file U1.1 after month end
5
Formats in play: XML, Excel, EDIFACT, PDF, email
4
Transmission channels under Circular 23/833
Who reports what
Some obligations apply to every UCI. Others depend on the vehicle: a SICAR does not file the same returns as a guaranteed UCITS.
All UCIs
UCITS under Part I of the Law of 17 December 2010, Part II UCIs, SIFs under the Law of 13 February 2007, and SICARs under the Law of 15 June 2004.
U1.1Supervision documentsSAQ / SR / ML / LMOSRRC24/856
UCITS, Part II UCIs and SIFs
Annual accounts data, and money market fund reporting where the fund qualifies as an MMF.
O4.1O4.2MMF
UCITS only
Risk reporting, plus quarterly VaR and leverage reporting for the funds the CSSF designates by letter.
URRVaR & Leverage
SICARs, SIAGs and FIAAGs
Investment companies in risk capital, self-managed investment companies and internally managed AIFs.
K3.1SIAG
Every CSSF reporting obligation for UCIs
Scroll the table sideways to see the format, the channel and the legal basis. The reporting code stays in view.
| Code | Reporting | Who | Frequency | Deadline | Format | Transmission | Legal basis |
|---|---|---|---|---|---|---|---|
| U1.1 | U1.1 Reporting | All UCIs | Monthly | Within 10 calendar days of month end | XML | eDesk “1 Reporting” or API (S3) | Circular CSSF 15/627, as amended by Circular CSSF 25/871 |
| — | Documents relating to supervision | All UCIs | Quarterly, half-yearly or annual | Depends on the document | PDF-text or Excel | e-file or SOFiE | Sectoral laws; Circulars CSSF 19/708, 18/698, 11/512; joint Circular BCL 2014/237 – CSSF 14/588 |
| SAQ / SR / ML / LMO | Self-assessment questionnaire and auditor reports | All UCIs | Annual | 3 to 6 months after year end, depending on the document and the fund type | — | eDesk “Collective Investment Sector Reporting Tool” or API (S3) | Circular CSSF 21/790 |
| SRRC | AML/CFT summary report RC | All UCIs | Annual | Within 5 months of financial year end | — | eDesk “AML/CFT Summary report RC” or API (S3) | Article 42(7) of CSSF Regulation No 12-02; Circular CSSF 24/854 |
| — | UCI notification under Circular 24/856 | All UCIs | Ad hoc | 4 to 8 weeks from detection of the error | — | eDesk “UCI notification” or API (S3) | Circular CSSF 24/856 |
| O4.1 / O4.2 | O4.1 and O4.2 Reporting | UCITS, Part II UCIs, SIFs | Annual | Within 10 days of financial year end | EDIFACT | e-file or SOFiE | Circulars IML 97/136 and CSSF 07/310, as amended by Circular CSSF 08/348 |
| MMF | MMF Reporting | UCITS, Part II UCIs, SIFs | Quarterly or annual, depending on assets under management | Within 30 days of the quarter or year end | XML | e-file or SOFiE | Article 37 of Regulation (EU) 2017/1131; Circulars CSSF 20/734, 20/736 and 26/911 |
| O1.2 | O1.2 Reporting | Guaranteed UCITS and Part II UCIs | Monthly | Within 10 calendar days of month end | XML | e-file or SOFiE | Article 147 of the Law of 17 December 2010 |
| URR | URR Reporting | UCITS | Half-yearly | No later than 6 weeks after the reference date | Excel | By email to URR_reporting@cssf.lu | Article 147 of the Law of 17 December 2010 |
| VaR | VaR & Leverage reporting | UCITS | Quarterly | No later than 6 weeks after the reference date | Excel | By email to URR_reporting@cssf.lu | Article 147 of the Law of 17 December 2010 |
| K3.1 | K3.1 Reporting | SICARs | Half-yearly, at 30 June and 31 December | Within 45 calendar days of the reference date | Excel | e-file or SOFiE | Circular CSSF 08/376 |
| SIAG | SIAG and FIAAG reporting | SIAGs and FIAAGs | Quarterly | By the 20th of the month following the reference date | Excel | By email to siag@cssf.lu | Circular CSSF 18/698 |
The reporting calendar
Read down the year rather than across the table: this is what actually lands on a fund administrator’s desk.
- Every monthU1.1 within 10 calendar days; O1.2 within 10 calendar days for guaranteed funds.
- Every quarterVaR & Leverage within 6 weeks; SIAG and FIAAG by the 20th of the following month; MMF within 30 days where quarterly.
- Twice a yearURR within 6 weeks; K3.1 within 45 calendar days of 30 June and 31 December.
- Once a yearO4.1 and O4.2 within 10 days of year end; SAQ, SR, ML and LMO on their own staggered deadlines; SRRC within 5 months.
- Whenever it happensCircular 24/856 notification, 4 to 8 weeks from the moment the error is detected.
The four transmission channels
Under Circular CSSF 23/833, and depending on the reporting concerned, professionals may use:
eDesk
The CSSF portal. Used for U1.1, the SAQ, the SRRC and Circular 24/856 notifications.
API (S3)
The CSSF interface, an alternative to eDesk for the same returns.
MFT
Managed file transfer, for the approaches the CSSF designates.
e-file and SOFiE
External channels, used for O4.1, O4.2, O1.2, MMF, K3.1 and supervision documents.
Two returns still travel by email. URR and VaR & Leverage go to URR_reporting@cssf.lu, SIAG and FIAAG reporting to siag@cssf.lu. Their Excel templates are fixed: columns and fields cannot be added, removed or reordered.
Where UCI reporting goes wrong
The obligations are published; what catches teams out is the mechanics.
| Cause | What happens |
|---|---|
| Ten calendar days, not ten working days | U1.1 and O1.2 both run on calendar days. A month ending on a Friday leaves far less room than it appears. |
| Identifiers that drift | The CSSF technical document Identifiers of UCI/SIF/SICAR governs the codes for funds, compartments and share classes. A compartment renamed internally but not re-declared breaks the match. |
| Compartment-level reporting | Several returns are filed per compartment, not per umbrella. Aggregating them produces a file that validates and is wrong. |
| Shared tables, two authorities | Certain O, U and S tables are shared between the CSSF and the BCL. The CSSF publishes instructions for prudential reporting only; the S tables belong to the BCL. |
| A modified audit opinion | It triggers the LMO within one month of the annual report, on top of the usual cycle. It is easy to miss because nothing schedules it. |
| The Excel template edited | URR and VaR templates are predefined. Adding a column to make them easier to fill makes them unreadable at the other end. |
| Assuming the fund is out of scope | Guaranteed funds and highly leveraged UCITS are told by the CSSF, by email or letter, that they are in scope. If you think you qualify and have heard nothing, the CSSF asks you to contact it. |
Frequently asked questions
What is the U1.1 reporting?
Monthly financial information on the UCI, filed in XML within 10 calendar days of month end through eDesk or the API (S3) channel, under Circular CSSF 15/627 as amended by Circular CSSF 25/871. It applies to every UCI.
Which reports apply to a SICAR?
A SICAR files the obligations common to all UCIs — U1.1, supervision documents, SAQ and related auditor reports, SRRC and Circular 24/856 notifications — plus K3.1, its own half-yearly financial reporting at 30 June and 31 December, due within 45 calendar days.
Does an AIF report through its manager?
For the obligations of an alternative investment fund manager, the CSSF publishes a separate page, Reporting to be submitted by IFMs. The same applies to SIAGs and FIAAGs for their manager-level obligations.
Who handles the S tables?
The BCL. The CSSF’s instructions cover prudential reporting only. Some O, U and S tables are shared between the two, which is why the same data can appear in both frameworks.
What happens after a NAV calculation error?
Circular CSSF 24/856 requires a notification with detailed information on material NAV errors, breaches of investment rules and other specified errors. The window is four to eight weeks from the date the error is detected, through eDesk or the API.
Can these returns be produced from Excel?
Several already are — URR, VaR, K3.1 and SIAG use CSSF Excel templates. For the XML returns, U1.1 and O1.2, the data usually starts in a spreadsheet and has to be converted. That conversion is what our U1.1 solution does.
Sources and related
Source: CSSF, Reporting to be submitted by UCIs, last updated 26 May 2026. Circulars and technical documents are linked from that page.
Twelve returns, one process
Fund XP builds the Excel solutions that turn your data into the exact file the CSSF accepts — U1.1 in XML, and the rest of the Luxembourg reporting stack.
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