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Circular CSSF 26/911: Luxembourg Money Market Funds, MMFR Stress Tests, and the 2026 Reporting Date
Use Circular CSSF 26/911: Luxembourg Money Market Funds, MMFR Stress Tests, and the 2026 Reporting Date when a CSSF circular repeal or amendment needs to be translated into governance and control updates. It explains understanding what a CSSF circular change or repeal does to references, affected UCI or fund actors, dates, controls, and evidence files, then shows how to identify the repealed or amended reference, affected actors, effective date, policy updates, and evidence needed for governance records. The later sections connect quick scan, key dates, and who is affected so the next step is easier to judge. Read it before updating policies or controls so the repealed reference, affected scope, and evidence trail are clear.
On May 19, 2026, the CSSF published Circular CSSF 26/911. The circular concerns ESMA guidelines on stress test scenarios under Article 28 of Regulation (EU) 2017/1131 on money market funds. The CSSF page states that the circular updates the 2025 ESMA stress-test scenario guidance and replaces Circular CSSF 25/877.
Direct Answer
Luxembourg money market funds and the managers or service providers responsible for their regulatory reporting should treat Circular CSSF 26/911 as the current CSSF circular for the 2025 ESMA MMF stress-test update. The practical date to watch is June 30, 2026, because the CSSF source identifies reporting implications from that date.
Quick scan
- Check whether the fund is an MMF under Regulation (EU) 2017/1131.
- Verify that internal references now cite Circular CSSF 26/911 instead of Circular CSSF 25/877.
- Review whether the June 30, 2026 reporting implication affects calendars, templates or ownership.
- Keep the official CSSF circular and the referenced ESMA materials as the live technical source.
- Escalate if reporting teams still rely on stale scenario assumptions or unclear ownership.
| Reader question | Practical answer |
|---|---|
| Does this apply to every Luxembourg fund? | No. The source is about money market funds under the MMF Regulation stress-test framework. |
| Is Circular CSSF 25/877 still the current circular? | No. The CSSF source says Circular CSSF 26/911 replaces Circular CSSF 25/877. |
| Is this an investor recommendation? | No. It is a regulatory reporting and stress-test source, not a signal to buy, sell, or hold a fund. |
| What should operations teams do? | Confirm reporting templates, scenario data, governance ownership, and deadline readiness against the official source. |
Key Dates
| Date | Event |
|---|---|
| May 19, 2026 | CSSF published Circular CSSF 26/911. |
| June 30, 2026 | CSSF source identifies reporting implications from this date. |
| June 2, 2026 | This article checked the official CSSF source. |
Who Is Affected
The primary audience is Luxembourg money market funds, their management companies or AIFMs where relevant, risk-management teams, compliance officers, fund boards, depositaries, administrators, auditors, and service providers that support MMF reporting or stress-test processes.
Retail and professional investors may still benefit from the article, but the user task is different. An investor should understand that stress testing is part of the regulatory and risk-management framework. The investor should not infer fund quality or suitability from the existence of a circular alone.
What Changed
The CSSF source identifies Circular CSSF 26/911 as replacing Circular CSSF 25/877. Editorially, that means pages and checklists that cite Circular CSSF 25/877 as current need an update. Operationally, teams should verify whether their 2026 reporting calendar, stress-test assumptions, system templates, and review process reflect the 2025 ESMA update referenced by the CSSF.
This article intentionally does not reproduce the technical scenario values. MMF reporting teams should use the official CSSF circular and the ESMA materials it references for the live technical basis.
Practical Checklist
| Check | Why it matters |
|---|---|
| Identify whether the fund is an MMF under Regulation (EU) 2017/1131. | The circular is tied to the MMF stress-test framework. |
| Replace stale references to Circular CSSF 25/877. | CSSF 26/911 is the current replacement source. |
| Confirm the June 30, 2026 reporting implication. | The date affects reporting readiness and internal calendars. |
| Map responsibility across risk, compliance, fund administration, and board reporting. | Stress-test reporting can fail when ownership is unclear. |
| Keep investor-facing explanations separate from regulatory operations. | Investors need plain-language risk context, not operational templates. |
Next-step checklist
- Gather the current MMF scope list, reporting calendar and template set for all affected funds.
- Check every current policy, checklist and operations note for stale references to Circular CSSF 25/877.
- Verify who owns scenario updates, XML or reporting templates, board reporting and sign-off before June 30, 2026.
- Save the official CSSF circular, the referenced ESMA materials and internal readiness evidence in one archive.
- Stop using a reporting template if the scenario basis or circular reference has not been refreshed.
- Escalate any mismatch between fund scope, reporting ownership and the official source timetable.
How This Fits the CSSF Fund Framework
Money market funds sit inside the broader Luxembourg investment-fund ecosystem, but they have specific EU MMF Regulation obligations. For broader source navigation, see CSSF investment fund regulatory framework in Luxembourg and Luxembourg CSSF rules tracker.
Source Review Status
Reviewed on June 4, 2026 against the official source URLs listed in this article. This publication batch excludes CSSF articles with official CSSF URLs that returned a non-200 HTTP status during the source check.
Official Sources
- CSSF: Circular CSSF 26/911
- CSSF: Circular CSSF 25/877
- CSSF: Investment fund industry regulatory framework
- EUR-Lex: Regulation (EU) 2017/1131 on money market funds
Bottom Line
Circular CSSF 26/911 is a current-source update for Luxembourg MMF stress-test coverage. The essential reader message is specific: use CSSF 26/911 instead of CSSF 25/877 for the current circular reference, and verify reporting readiness for the June 30, 2026 implications through the official source.
Batch 10 authority and next-step check
For CSSF MMFR liquidity evidence for money market funds, the useful decision is not one document in isolation. Compare identity, address, residence, tax, employment, health-cover and payment evidence against the institution that will actually review the file. Keep dated screenshots, application references and written replies together so a later reviewer can see what rule or request was current when you acted.
Official source baseline
- cssf.lu official source
- cssf.lu official source
- EUR-Lex official source
- esma.europa.eu official source
- eba.europa.eu official source
Related guides to cross-check
- cssf liquidity management tools edesk ucits aif 2026 guide
- cssf investment fund supervisory priorities 2026 guide
- cssf uci reporting obligations luxembourg calendar evidence guide
- cssf ucits risk management process luxembourg guide
- cssf investment fund regulatory framework luxembourg
Decision test before relying on the file
- Confirm which authority, bank, employer, landlord, school or provider will make the decision.
- Separate facts that prove identity, address, legal stay, work status, tax residence, insurance cover, payment capacity and family status.
- Record deadlines, appointment dates, issue dates, translation requirements, appeal routes and any request for originals.
- Ask for a written answer when the rule depends on your specific facts or on a local office's implementation.
- Use this page as general information, not legal, tax, immigration, investment, health or benefits advice.
When the answer could affect legal status, regulated financial services, employment rights, taxes, public benefits, family rights or health cover, recheck current rules with the competent authority or a qualified adviser before making a commitment.