CSSF Reporting Calendar Q2 2026: Every Deadline Luxembourg Banks and Fund Managers Need This Quarter

Last updated: April 2026

Miss a COREP remittance by one day and the CSSF will notice. Miss a CRS filing deadline and the ACD will notice even faster. Q2 is the quarter where annual filings, quarterly prudential reports, and ongoing transaction reporting obligations all converge on the same teams, often the same individuals, at the same time.

I have watched Q2 catch reporting teams off guard more than any other quarter. The reason is simple: the Q1 quarterly reference date (31 March) triggers a cluster of prudential remittances in May, while June brings the annual tax exchange deadlines. Layer in monthly liquidity reporting, ongoing EMIR and MiFIR obligations, DORA register maintenance, and the annual accounts filing window, and the calendar gets dense fast.

This article is a month-by-month reference for every reporting obligation due between April and June 2026, covering both credit institutions and fund managers operating under CSSF supervision. I keep it updated as circulars or EBA communications shift dates. Bookmark it.

Related reading: COREP Reporting Explained

How to Use This Calendar

The deadlines below are grouped by month, then by entity type (banks first, then fund managers, then obligations that apply to both). Where a deadline falls on a weekend or Luxembourg public holiday, the standard rule under most EBA and CSSF frameworks is to shift to the next business day. But do not assume this applies everywhere. FATCA and CRS deadlines under the ACD (Administration des Contributions Directes) do not always follow the same convention.

Each entry includes the framework, the reference period, the submission channel (where known), and the legal basis. The legal basis matters because when something goes wrong, “the EBA website said so” is not a defence your compliance officer will accept.

One mistake I see regularly: teams tracking only the EBA remittance calendar without cross-checking CSSF-specific national requirements. The CSSF layers additional reporting on top of EBA harmonised frameworks. If you only watch the EBA calendar, you will miss the BCL statistical returns and CSSF-specific tables that run on different cycles.

April 2026

Credit Institutions

April is dominated by monthly recurring submissions and the annual accounts filing deadline.

Monthly LCR (reference date: 28 February 2026). The remittance window is 30 calendar days from the reference date, which puts this at 30 March. But if your institution files on T+30 from month-end and the March submission window overlaps into early April due to processing lags, confirm your exact CSSF submission window. Significant institutions (SIs) under direct ECB supervision file via the ECB’s CASPER portal. Less significant institutions (LSIs) file through the CSSF’s own reporting channels.

Monthly ALMM (Additional Liquidity Monitoring Metrics) for SIs. Same reference date cycle. ALMM templates C 66.00 through C 71.00 follow the same 30-calendar-day remittance rule as LCR for monthly reporters. This catches out teams who treat ALMM as an afterthought because the templates are shorter. The data quality checks are just as strict.

BCL statistical reporting. The Banque Centrale du Luxembourg requires monthly balance sheet statistics (BSI reporting) from all monetary financial institutions. The typical deadline is the 15th business day after month-end. For the March 2026 reference date, that lands around 22 April 2026. The BCL portal (S3 – Collecte Statistique) is the submission channel.

Annual accounts submission. Under Luxembourg law (Article 71 of the Law of 19 December 2002 as amended) and CSSF Circular 15/606, credit institutions with a December year-end must file their annual accounts with the CSSF within four months of the financial year-end. That deadline is 30 April 2026. This includes audited financial statements, the management report, and the auditor’s report. Filing is through the CSSF eRIIS portal. Do not confuse this with the RCS (Registre de Commerce et des Societes) filing, which has its own separate deadline.

The common trap here: the four-month rule applies to the CSSF filing. The shareholder approval (AGM) may happen later, but the CSSF expects the accounts by 30 April regardless. If your AGM is scheduled for May, you still need to file the accounts as approved by the board, with a note that shareholder approval is pending.

Fund Managers

AIFMD Annex IV reporting (Q1 2026, quarterly reporters). Under Article 110 of the AIFMD Delegated Regulation (EU) No 231/2013 and CSSF Circular 18/698, AIFMs reporting quarterly must submit their Annex IV data within 30 calendar days of the quarter-end. For Q1 2026 (reference date 31 March), the deadline is 30 April 2026. Submission is through the CSSF’s eRIIS portal.

The quarterly threshold matters: AIFMs managing portfolios above EUR 1 billion (for leveraged AIF strategies) or EUR 1.5 billion (for unleveraged strategies) report quarterly. Below those thresholds, you report semi-annually or annually. I have seen firms miscalculate their AuM threshold and file on the wrong frequency for an entire year before anyone flagged it. Verify your classification every January.

UCI monthly reporting (O 1.1 tables). Management companies and self-managed SICAVs submit monthly net asset data to the CSSF. The standard deadline is 20 calendar days after month-end. For the March reference period, that is around 20 April 2026.

CESOP (Central Electronic System of Payment Information). Payment service providers, including e-money institutions operating in Luxembourg, must file quarterly CESOP reports. The Q1 2026 report (covering January-March) is due by 30 April 2026. This covers cross-border payment data exceeding 25 transactions per payee per quarter. Filed through the Luxembourg tax authority portal.

All Entities

EMIR trade reporting. Daily and ongoing. No quarterly spike, but Q2 is when many firms run their first full quarterly reconciliation against trade repositories under the EMIR Refit framework, notably Regulation (EU) 2019/834 (EMIR Refit) together with the delegated and implementing reporting rules including Commission Delegated Regulation (EU) 2022/1855 and Commission Implementing Regulation (EU) 2022/1860. If your reconciliation process is not yet stable after the 2024 refit reporting go-live, April is when gaps in your pairing and matching rates will become visible in the ESMA data quality reports.

MiFIR transaction reporting. Daily and ongoing under Article 26 of MiFIR. No specific Q2 deadline shift, but the CSSF typically runs its annual data quality review in Q2, based on the full prior-year dataset. Expect ad hoc queries from the CSSF if your rejection rates spiked in 2025.

May 2026

Credit Institutions

This is the month where Q1 prudential reporting lands. The reference date is 31 March 2026, and the remittance clock starts ticking.

Quarterly COREP Own Funds (C 01.00 – C 06.02) and COREP Credit Risk (C 07.00 – C 14.01). For significant institutions, the EBA ITS on supervisory reporting (Commission Implementing Regulation (EU) 2024/3117, as amended) sets the quarterly remittance at 42 calendar days from the reference date. 31 March + 42 days = 12 May 2026. This is the hard deadline for SIs. Less significant institutions under CSSF direct supervision follow the same 42-day rule in practice, though the ITS technically allows NCAs to set a longer window of up to 72 calendar days for smaller firms.

Quarterly FINREP (F 01.01 – F 46.00). Same remittance date as COREP for institutions reporting on a solo and/or consolidated basis. 12 May 2026 for SIs. FINREP covers the full suite of financial reporting templates under IFRS or national GAAP, depending on your reporting framework election. The CSSF expects XBRL-tagged submissions through the EBA filing platform.

Where teams consistently stumble: the Q1 FINREP submission requires a fresh P&L (templates F 02.00 and F 03.00) that resets from the January-March period. This is the first quarterly P&L after the annual close. If your annual accounts are not yet finalised by early May, you may be filing FINREP Q1 based on preliminary management accounts. That is acceptable, but you need to reconcile and resubmit if material adjustments emerge from the audit. The CSSF does not issue formal guidance on materiality thresholds for resubmission, which means your internal policy needs to define what “material” means.

Quarterly Large Exposures (C 26.00 – C 29.00). Same 12 May 2026 deadline as COREP. The LE templates follow the COREP remittance cycle. The trap here is connected client identification: Q1 is when annual reviews of connected client groups should be complete, and any reclassifications need to flow through to the LE templates before the May filing.

Quarterly NSFR (C 80.00 – C 84.00). Due alongside COREP, 12 May 2026 for SIs. Unlike the LCR (monthly for SIs), NSFR is quarterly only. The common problem: NSFR templates require a different categorisation of liabilities than the LCR, and teams sometimes copy LCR bucket mappings into NSFR without adjusting for the longer time horizon. The CSSF’s validation rules will catch some of these, but not all.

MREL reporting (M 01.00 – M 07.00). Quarterly, with reference date 31 March 2026. The remittance period under the ITS on MREL reporting is approximately 49 calendar days. For Q1 2026, that puts the deadline around 19 May 2026. Submission through the SRB’s reporting channel for entities under SRB resolution planning, or through the CSSF for entities under national resolution authority scope. Be precise about which authority you report to. The SRB and CSSF do not share your data automatically.

Monthly LCR (reference date: 31 March 2026). Due by 30 April. But the April monthly LCR (reference date: 30 April) is due by 30 May 2026. Do not confuse the quarterly COREP LCR template (C 72.00-C 76.01, due 12 May) with the monthly LCR supervisory reporting. They cover the same ratio but serve different purposes and have different remittance dates.

BCL statistical reporting for April reference date. Due around 22 May 2026 (15th business day).

Fund Managers

No major quarterly fund reporting deadlines in May for most managers. However, management companies should be preparing Q2 data collection processes, and any semi-annual AIFMD reporters (reference date 31 December 2025) who received extensions should confirm their filings are complete.

UCI semi-annual reports. UCITS with a 31 December financial year-end must publish their semi-annual report (covering July-December 2025) within two months of the period-end. That deadline was 28 February 2026. But management companies sometimes delay the CSSF filing beyond the publication date. If you have not yet filed the semi-annual report with the CSSF by May, you are late.

June 2026

Credit Institutions

Quarterly COREP/FINREP for LSIs (extended remittance). If your institution operates under the 72-calendar-day remittance window (applicable to certain less significant institutions as determined by the CSSF), the Q1 2026 COREP and FINREP deadline falls on 11 June 2026 (31 March + 72 days). Confirm with your CSSF reporting contact whether you are on the 42-day or 72-day cycle. The CSSF does not publish a public list of which institutions are on which cycle.

Monthly LCR (reference date: 31 May 2026). Due by 30 June 2026.

BCL statistical reporting for May reference date. Due around 22 June 2026.

Pillar 3 disclosures. Large institutions and listed entities must publish their annual Pillar 3 disclosure report concurrent with or shortly after the publication of their annual financial statements. Under CRR Article 433, the annual disclosure reference date is 31 December 2025, and the expectation is publication alongside the annual report. For most Luxembourg banks, this means Q2 2026 is when the Pillar 3 report should be publicly available. The CSSF monitors publication but does not set a fixed calendar date for this. If your annual report was published in April, your Pillar 3 disclosure should already be out.

The problem I see every year: Pillar 3 is treated as a compliance document rather than a disclosure commitment. Teams finalise it weeks after the annual report, which technically puts them in breach of the “concurrent publication” expectation. The EBA has flagged this pattern in its annual Pillar 3 assessment reports.

Fund Managers

Annual AIFMD Annex IV (annual reporters). AIFMs below the quarterly reporting threshold (managing AIF portfolios under EUR 1 billion for leveraged strategies, or under EUR 1.5 billion for unleveraged) file annual Annex IV data with a reference date of 31 December 2025. The deadline is 30 calendar days after the year-end, which would be 30 January 2026. However, the CSSF has historically provided operational extensions for annual reporters, pushing the effective deadline into Q1 or early Q2. If you have not filed by June 2026 for the 2025 reference period, you are unambiguously late.

UCI annual reports (December year-end). Under Article 156 of the Law of 17 December 2010, UCITS must publish annual reports within four months of the financial year-end. For December year-end funds, that is 30 April 2026. But the filing with the CSSF and the actual dissemination to investors sometimes drift into May or June. The CSSF expects the filing to be contemporaneous with publication.

Tax Reporting: CRS and FATCA

This is the big one for June. Both deadlines hit on 30 June 2026.

CRS (Common Reporting Standard). Luxembourg reporting financial institutions must file their CRS reports for the 2025 calendar year with the ACD (Administration des Contributions Directes) by 30 June 2026. The legal basis is the Law of 18 December 2015 (transposing DAC2/Council Directive 2014/107/EU) and the OECD CRS framework. Filing is through the ACD’s MyGuichet platform.

FATCA (Foreign Account Tax Compliance Act). Same deadline: 30 June 2026 for the 2025 reporting year. The legal basis is the Luxembourg IGA (Intergovernmental Agreement with the United States, signed 28 March 2014) and the Law of 24 July 2015. Filed through the same ACD channel.

The operational trap with CRS and FATCA is not the filing itself. It is the remediation of undocumented accounts. By 30 June, any accounts that were undocumented at 31 December 2025 must either be documented or reported as undocumented. I have seen institutions delay their self-certification campaigns until Q2, then scramble to process hundreds of client responses in the weeks before the filing deadline. Start the campaigns in Q1. By April, you should know which accounts remain undocumented and be preparing the exception reports.

Do not confuse CRS/FATCA with CARF (Crypto-Asset Reporting Framework). CARF has been adopted at EU level through DAC8 (Council Directive (EU) 2023/2226), but the first CARF reporting deadline for Luxembourg is not until 2027 (for the 2026 reporting period). It is not a Q2 2026 obligation.

All Entities

DAC6 (Mandatory Disclosure Rules). DAC6 has no quarterly deadline. The reporting obligation is triggered within 30 days of a reportable cross-border arrangement being made available, ready for implementation, or the first step being implemented (whichever occurs first). This runs continuously throughout Q2. But June is when many firms conduct their semi-annual DAC6 compliance review to ensure no arrangements were missed. Under Luxembourg’s Law of 25 March 2020, the reporting is filed with the ACD.

SFTR (Securities Financing Transactions Regulation). Daily reporting, ongoing. No Q2-specific deadline. But ESMA’s data quality reviews in Q2 2026 may surface reconciliation issues from Q1. If your matching rates dropped below ESMA’s thresholds, expect outreach from your trade repository or the CSSF.

DORA Register of Information. Under Article 28(3) of DORA (Regulation (EU) 2022/2554), financial entities must maintain a register of all ICT third-party service arrangements. The register must be kept up to date. There is no fixed quarterly remittance date in Q2 2026, but the CSSF may request the register at any time for supervisory purposes. The ESAs published the final RTS on the register content (RTS on the register of information under DORA) in early 2025. If your register is not current by Q2 2026, you have a gap. Use Q2 to reconcile your register against new or terminated contracts from Q1.

Public Holidays That Shift Deadlines

Luxembourg has several public holidays in Q2 that can push reporting deadlines:

• 1 May 2026 (Labour Day) – Friday. If a deadline falls on 1 May, the submission shifts to 4 May (Monday). This directly affects any T+30 monthly reports with an April reference date.
• 14 May 2026 (Ascension Day) – Thursday. Close to the 12 May COREP/FINREP deadline. The prudential deadline itself is 12 May (Tuesday), so no conflict. But internal review timelines may be compressed if teams take the bridge day on Friday 15 May.
• 25 May 2026 (Whit Monday) – Monday. Impacts any end-of-May deadlines that might shift.
• 23 June 2026 (Luxembourg National Day) – Tuesday. One week before the CRS/FATCA deadline. Plan accordingly.

The EBA’s general approach: if a remittance date falls on a national holiday or weekend, submission is due on the next business day. But the ACD (for tax filings) and the BCL (for statistical reporting) may apply different conventions. Confirm with each authority individually.

Reporting Channels Summary

Knowing what to file is half the problem. Knowing where to file it is the other half. In Luxembourg, reporting teams typically operate across four or five separate portals in any given quarter.

• CSSF eRIIS portal: COREP, FINREP, Large Exposures, LCR, NSFR, ALMM, MREL (for entities under national resolution), AIFMD Annex IV, UCI reporting
• ECB CASPER: SIs under direct ECB supervision file prudential reports here (the data flows through the CSSF but the portal is ECB-operated)
• SRB reporting channel: MREL for entities under SRB resolution planning
• BCL S3 portal: Monthly and quarterly statistical reporting
• ACD MyGuichet: CRS, FATCA, DAC6
• Trade repositories (DTCC, Regis-TR, UnaVista, etc.): EMIR, SFTR daily reporting
• National Competent Authority (CSSF): MiFIR transaction reports (via ARMs or direct submission)

A recurring problem: portal access management. When staff leave and new team members join, portal credentials and access rights do not transfer automatically. I have seen a COREP submission delayed because the only person with eRIIS upload rights was on leave and nobody had requested backup access. Q2 is a good time to audit your portal access list. Confirm that at least two people can submit to each channel.

What Changed Since Q1 2026

Two developments affect Q2 reporting:

CRR3/CRD6 implementation. The CRR3 (Regulation (EU) 2024/1623) output floor and revised standardised approaches took effect on 1 January 2025. The Q1 2026 COREP submission (due May 2026) is the fifth quarterly filing under the new framework. By now, the initial implementation issues should be resolved. But the CSSF has indicated it will increase data quality scrutiny on CRR3-affected templates starting in Q2 2026, particularly on the output floor calculation (template C 03.00) and the revised credit risk standardised approach (C 07.00 series). If your validation rule failures spiked in the Q4 2025 or Q1 2026 submissions, expect follow-up questions.

DORA full application. DORA has been fully applicable since 17 January 2025. The Q2 2026 period is when the CSSF is expected to shift from a “monitoring” posture to active enforcement of the register of information requirements and ICT incident reporting obligations. If you have not yet filed your register of information or tested your major ICT incident classification and reporting workflow, you are behind the curve.

Building a Workable Q2 Schedule

Here is how I approach Q2 planning for a Luxembourg credit institution that also has fund management activities.

First week of April: confirm all portal access credentials are current. Run a test upload on each platform if the portal supports it. Start the CRS/FATCA remediation campaign for undocumented accounts.

Mid-April: finalise annual accounts for CSSF submission (30 April deadline). Complete monthly LCR and BCL statistical submissions.

Last week of April: begin COREP/FINREP Q1 data extraction and template population. File AIFMD Annex IV for quarterly reporters. Submit CESOP Q1 if applicable.

First week of May: internal review of COREP/FINREP templates. Run EBA validation rules locally before submission. Cross-check Large Exposures connected client groups against Q1 changes.

12 May: submit COREP, FINREP, Large Exposures, LCR (quarterly template), NSFR.

19 May: submit MREL quarterly (confirm exact date with your resolution authority).

June: focus shifts to CRS/FATCA preparation. Finalise exception reports for undocumented accounts. Prepare Pillar 3 disclosure if not already published. Reconcile DORA register of information.

30 June: submit CRS and FATCA to ACD via MyGuichet.

This timeline assumes a December year-end. If your institution has a non-standard financial year-end, adjust the annual accounts and Pillar 3 deadlines accordingly.

Related Articles

• COREP Reporting Explained – Full guide to COREP templates, validation rules, and common errors for Luxembourg credit institutions.
• FINREP Reporting Explained – How FINREP works, which templates apply, and what the CSSF expects from solo and consolidated reporters.
• Liquidity Reporting for Luxembourg Banks – LCR, NSFR, and Additional Monitoring Metrics – Detailed breakdown of liquidity reporting obligations and common pitfalls.
• MREL Reporting Requirements – Templates, frequency, and what your resolution authority expects.
• Large Exposures Reporting for Luxembourg Banks – COREP LE templates and connected client requirements.
• DORA Register of Information – Practical guide to building and maintaining your ICT third-party register.

Sources and References

• Commission Implementing Regulation (EU) 2024/3117 on supervisory reporting (ITS on reporting) – EUR-Lex
• Regulation (EU) No 575/2013 (CRR) as amended by Regulation (EU) 2024/1623 (CRR3) – EUR-Lex
• Directive 2011/61/EU (AIFMD) and Commission Delegated Regulation (EU) No 231/2013 – EUR-Lex
• Council Directive 2014/107/EU (DAC2 – CRS) – EUR-Lex
• Luxembourg Law of 18 December 2015 (CRS transposition) – Legilux
• Luxembourg Law of 24 July 2015 (FATCA) – Legilux
• Regulation (EU) 2022/2554 (DORA) – EUR-Lex
• CSSF Circular 15/606 (annual accounts filing) – CSSF
• CSSF Circular 18/698 (AIFMD reporting) – CSSF
• Council Directive (EU) 2023/2226 (DAC8 – CARF) – EUR-Lex
• Regulation (EU) 2019/834 (EMIR Refit) – EUR-Lex
• Commission Delegated Regulation (EU) 2022/1855 supplementing EMIR reporting rules – EUR-Lex
• Commission Implementing Regulation (EU) 2022/1860 laying down EMIR reporting technical standards – EUR-Lex
• Council Directive (EU) 2020/284 and Council Regulation (EU) 2020/283 on CESOP – EUR-Lex
• Regulation (EU) 2024/886 (Instant Payments Regulation) – EUR-Lex

Disclaimer: The information on RegReportingDesk.com is for educational and informational purposes only. It does not constitute legal, regulatory, tax, or compliance advice. Always consult your compliance officer, legal counsel, or the relevant supervisory authority for guidance specific to your institution.