Luxembourg CRS: ACD updates XSD 3.0 migration timeline

On 8 September 2026, the Luxembourg Direct Tax Administration (Administration des contributions directes or ACD) released an updated set of Frequently Asked Questions (FAQ) concerning the amended Law of 18 December 2015 on the Common Reporting Standard (CRS). On the same date, the ACD announced a pre-validation environment would be available for the new CRS XSD Schema v3.0.

The updates clarify the documentation applicable under the current and as well as the revised CRS frameworks, the treatment of electronic money institutions and payment institutions, the processing of CRS reports, reporting identifiers, Tax Identification Number (TIN) requirements, and clarifies the reporting of undocumented accounts. They also establish the anticipated timetable for testing and implementing CRS XSD Schema v3.0. This Tax Alert summarizes the main changes and the practical steps that Luxembourg Reporting Financial Institutions (RFI) should consider.

Updated CRS documentation

Question 1.1 of the FAQs has been revised to distinguish between the CRS documentation applicable until 31 December 2026, and the documentation that will apply as of 1 January 2027. The ACD has also released CRS XSD Schema v3.0 and a corresponding CRS User Manual.

According to the updated FAQs, the existing CRS XSD Schema v2.0 and ECHA Circular No. 4 of 10 August 2020 will no longer apply for CRS reporting purposes from as of 1 January 2027. RFIs should therefore review the new documentation and assess the changes required to their CRS reporting processes, data models, and technical interfaces.

Electronic money institutions and payment institutions

Question 2.6 has been updated following the adoption of the Law of 27 March 2026. The revised guidance clarifies that Specific Electronic Money Products (SEMP) and Central Bank Digital Currencies (CBDC) are included within the expanded scope of CRS 2.0. As a result, electronic money institutions and payment institutions may fall within the scope of CRS 2.0 with effect as of 1 January 2026.

Entities providing electronic money or payment services should reassess their CRS classification and determine whether their products, accounts, or activities give rise to due diligence or reporting obligations. This review should also consider whether systems currently capture the customer, tax-residence, and account information required under the expanded framework.

Processing and validation of CRS reports

Question 5.2 simplifies and clarifies the information concerning the ACD’s processing of submitted CRS data. CRS reports are not processed instantaneously but instead through batch-validation cycles. The frequency of those cycles varies according to the submission portal used. Processing times may consequently increase as the 30 June annual reporting deadline approaches.

RFIs should therefore avoid submitting their reports during the final days before the deadline. Sufficient time should be allowed to both receive and review validation results, investigate warnings or errors and, where necessary, submit corrected reports.

Reporting where an RFI has no Luxembourg TIN

Question 5.4 has been revised to distinguish between two situations in which an RFI does not have its own Luxembourg TIN.

RFI with another Luxembourg identifier

Where an RFI has a Luxembourg identifier other than a TIN, such as a sub-fund with a compartment number issued by the Commission de Surveillance du Secteur Financier (CSSF), the RFI must report the Luxembourg registration number of its parent entity or umbrella fund, supplemented by its own identifier using the letter “F”.

RFI without any Luxembourg identifier

Where an RFI has no Luxembourg identifier, for example, a foreign trust with a Luxembourg trustee, it must first request a sequential number from the ACD. That number must be reported as a supplement to the registration number of the parent entity, trustee or other relevant associated entity, using the letter “T”.

Affected entities should review their identifiers before preparing their next CRS submission. Where an ACD sequential number is required, it should be requested sufficiently in advance of the relevant reporting deadline.

Mandatory TINs for new EU accounts

Question 5.7 addresses the use of the substitute code #NTA001# where a TIN is unavailable. With effect from 1 January 2026, reporting a TIN is mandatory for New Accounts held by tax residents of EU jurisdictions.

The code #NTA001# may continue to be used as a last resort where a TIN is unavailable. However, its use will generate a warning message, particularly where the submitted report states that a valid self-certification has been obtained.

RFIs should review their onboarding and remediation controls to ensure that TINs are collected and validated for New Accounts held by EU tax residents. They should also investigate cases in which a valid self-certification document has been recorded but the corresponding TIN remains unavailable.

Reporting of undocumented accounts

A new Question 5.11 explains when a Pre-existing Individual Account is treated as an undocumented account. This applies where:

The only indicium identified is either a hold-mail instruction or an “in-care-of” address in a Reportable Jurisdiction;
No other indicia of residence have been identified; and
The required due diligence procedures, including a paper record search and attempts to obtain a self-certification, have failed to establish the Account Holder’s jurisdiction of tax residence.

Such an account must be reported by:

Setting the ‘UndocumentedAccount’ attribute of the <AccountNumber> element to true; and
Using the country code LU as the destination jurisdiction in the ‘DocRefId’ element.

RFIs should confirm that their systems can identify these accounts and populate both technical fields correctly. The due diligence steps performed and attempts to obtain a self-certification document should also be documented and retained.

CRS XSD Schema v3.0 pre-validation environment

The ACD announced that a pre-validation environment for CRS XSD Schema v3.0 will be available from 12 October 2026. The environment is intended to allow Luxembourg RFIs to test their reporting systems before the new submission requirements take effect on 1 January 2027. Technical specifications are included in the CRS User Manual available through the ACD’s “Electronic Exchanges” section.

The production environment for submitting CRS reports using XSD Schema v3.0 is expected to become available on 25 January 2027. However, the ACD has indicated that this date remains provisional and will be confirmed in the coming months.

Schema transition dates require attention

The ACD announcement states that submissions using CRS XSD Schema v2.0 will no longer be accepted as of 30 September 2026. Separately, the updated FAQs state that CRS XSD Schema v2.0 and ECHA Circular No. 4 will no longer apply as of 1 January 2027.

These statements appear to describe different transition milestones, but may create uncertainty regarding submissions or corrections required between 30 September 2026 and 31 December 2026. RFIs should therefore monitor further ACD communications and confirm the applicable filing arrangements before making submissions during this period.

Practical next steps

Luxembourg RFIs should consider taking the following actions:

Assess the impact of CRS XSD Schema v3.0:

Compare existing data structures and reporting processes with the new schema and CRS User Manual.
Prepare for pre-validation:

Develop a testing plan, prepare representative test files and assign responsibility for analyzing validation results from 12 October 2026.
Clarify the transition timetable:

Confirm the treatment of original, corrective and replacement submissions after 30 September 2026.
Review entity classifications:

Determine whether electronic money institutions, payment institutions, SEMPs or CBDCs are brought within the expanded CRS scope.
Strengthen TIN controls:

Review New Accounts held by EU tax residents and remediate missing TINs or inconsistencies involving valid self-certifications.
Identify undocumented accounts:

Ensure that qualifying accounts are flagged and reported using the required attributes and destination jurisdiction.
Advance the reporting timetable:

Allow sufficient time before the 30 June deadline for batch validation, error remediation and corrective filings.
Monitor ACD publications:

Follow further announcements confirming the CRS XSD Schema v3.0 production date and transitional filing arrangements.

Conclusion

The updated FAQs and the announced CRS XSD Schema v3.0 testing environment represent significant operational developments for Luxembourg RFIs. In addition to preparing for a new technical reporting schema, institutions must address revised rules concerning electronic money and CBDCs, reporting identifiers, mandatory TINs, undocumented accounts, and batch-validation timelines.

The pre-validation environment scheduled for 12 October 2026 provides an important opportunity to test reporting systems before CRS XSD Schema v3.0 becomes mandatory from 1 January 2027. However, RFIs should seek clarity on the statement that submissions under XSD Schema v2.0 will no longer be accepted as of 30 September 2026 and should monitor the ACD’s confirmation of the provisional production date of 25 January 2027.

What's next?

RFIs should begin their technical and operational preparations without delay, including schema mapping, test-file preparation, identifier remediation and the review of account-level due diligence data. Further ACD guidance is expected concerning the transition between schema versions and the availability of the production environment.

KPMG Tax teams stand ready to assist with CRS impact assessments, entity-classification reviews, data and process gap analyses, technical schema implementation, pre-validation testing, and remediation planning.