Adoption of the euro by Bulgaria

2, boulevard Royal  L-2983 Luxembourg  Télécopie (+352) 4774-4943  E-mail: stat@bcl.lu 1 / 4 Concerns: Adoption of the euro by Bulgaria Ladies and Gentlemen, On 8 July 2025, the EU Council formally approved the accession of Bulgaria to the euro area on 1 January 2026. The objective of the present circular letter is to clarify the impact of the adoption of the euro by Bulgaria for the establishment of the monthly and quarterly statistical reports. 1 Impact on the statistical data collection of the BCL The joining of the euro area by Bulgaria as from 1 January 2026 onwards will not only have an impact on the establishment of monthly and quarterly statistical reports but also on the calculation of the reserve requirement, which credit institutions are subject to.
1.1 Impact on the monthly statistical data collection
The monthly statistical reports:
 S 1.1 «Monthly statistical balance sheet of credit institutions»,  S 1.4 «Valuation effects on the statistical balance sheet of credit institutions»  S 1.5 «Information on interest rates in EUR»  S 1.8 «Securitisations and other loan transfers by credit institutions» require a breakdown of assets and liabilities according to the country of residency or the country of the registered office, i.e. the country where the centre of economic interest of a counterpart is located. Ref.: ST.25-0366 Luxembourg, 31 July 2025 To all credit institutions

2, boulevard Royal  L-2983 Luxembourg  Télécopie (+352) 4774-4943  E-mail: stat@bcl.lu 2 / 4 The following breakdowns are applicable:
 All countries: this category regroups all the operations regardless of the country of residency or the country of the registered office  Luxembourg (LU)  OMUMs: i.e. Other Monetary Union Member States  Rest of the world: i.e. the countries that are not included in the two aforementioned categories As from 1 January 2026, the category «Other Monetary Union Member States» (OMUMs) will also include Bulgaria that is currently, and until 31 December 2025, included in the category «Rest of the world».
1.2 Impact on the quarterly statistical data collection
The quarterly statistical report S 2.5 «Quarterly statistical balance sheet of credit institutions» requires a breakdown of assets and liabilities according to the country of residency or the country of the registered office by using a two digit ISO code. Since the economic sector breakdown is identical for all countries, the adoption of the euro by Bulgaria does not have any impact on report S 2.5 «Quarterly statistical balance sheet of credit institutions». 2 Impact for the calculation of the reserve requirement The liabilities which are owed to the European Central Bank (ECB), to the National Central Banks (NCBs) that are members of the Eurosystem and to credit institutions (CIS) that are subject to the Eurosystem's minimum reserve requirement are excluded from the reserve base. Therefore, the volume of liabilities included in the reserve base must be reduced by the amount of liabilities owed to credit institutions from Bulgaria that are subject to the Eurosystem's minimum reserve requirement as from January 2026 onwards. The volume of liabilities included in the reserve base must also be reduced by the amount of liabilities owed to the Bulgarian central bank.

2, boulevard Royal  L-2983 Luxembourg  Télécopie (+352) 4774-4943  E-mail: stat@bcl.lu 3 / 4 For the maintenance period starting 23 December 2025 and ending 10 February 2026 as well as the one starting 11 February 2026 and ending 24 March 2026, the liabilities owed to the National Central Bank of Bulgaria as well as to credit institutions from Bulgaria being subject to the Eurosystem's reserve requirement may already be deducted from the reserve base of credit institutions. Luxembourg credit institutions that wish to benefit from this option must fill in the attached table for October 2025 and December 2025 in order to inform the BCL about the positions against counterparts resident in Bulgaria. The BCL will adjust the reserve requirements reported based on report S 1.1 «Monthly statistical balance sheet of credit institutions» of October and December 2025 by taking into account the information provided in the attached table. Credit institutions are reminded that statistical reports S 1.1, S 1.4, S 1.5, S 1.8 and S 2.5 must be established by considering Bulgaria as not being a member of the Monetary Union until 31 December 2025 included. 3 Quality of the data transmitted Credit institutions are reminded to scrupulously check the correct identification of their counterparts and to use, in particular, the official list of credit institutions published by the Commission de Surveillance du Secteur Financier (CSSF) as well as the official list of monetary financial institutions made available to reporting agents on the website of the ECB. We therefore consider it necessary to stress once again the importance of the quality of the data transmitted to the BCL and the necessity to submit the data to the verification rules detailed in the technical documentation. Only a rigorous control undertaken during data production will allow respecting the quality requirements as well as the reporting delays. This is particularly important given that the collected data will be checked by the ECB before aggregating them with the data of the other Member States. Any error or important negligence will have harmful repercussions on the reputation of the Luxembourg financial community.

2, boulevard Royal  L-2983 Luxembourg  Télécopie (+352) 4774-4943  E-mail: stat@bcl.lu 4 / 4 4 Setting up of the new arrangements The new classification of assets and liabilities towards resident counterparts of Bulgaria must be implemented for the first time with regard to the monthly statistical reports referring to January 2026. The attached table relating to the calculation of minimum reserves refers to the periods of October and December 2025. Yours sincerely, BANQUE CENTRALE DU LUXEMBOURG Germain Stammet Xavier Hornick Deputy Head of department Head of section

Annex: 1
 Information to be provided to the Banque centrale du Luxembourg for the reduction of the reserve base relating to the periods of October and December 2025

July 2025
Information to be provided to the Banque centrale du Luxembourg for the reduction of the reserve base relating to the periods of October and December 2025

2. Liabilities
   Line Item Country Currency Economic sector <= 3 months > 3 months & <= 1 year > 1 year & <= 2 years > 2 years & <= 5 years > 5 years No breakdown 2-002010-BG-EUR-MRR02 Debts - Overnight deposits Bulgaria EUR Institutions subject to reserve requirements 2-002010-BG-XX2-MRR02 Bulgaria XX2 Institutions subject to reserve requirements 2-002020-BG-EUR-MRR02 Debts - Deposits with agreed maturity Bulgaria EUR Institutions subject to reserve requirements 2-002020-BG-XX2-MRR02 Bulgaria XX2 Institutions subject to reserve requirements 2-002030-BG-EUR-MRR02 Debts - Deposits redeemable at notice Bulgaria EUR Institutions subject to reserve requirements 2-002030-BG-XX2-MRR02 Bulgaria XX2 Institutions subject to reserve requirements 2-002040-BG-EUR-MRR02 Debts - Repurchase agreements Bulgaria EUR Institutions subject to reserve requirements 2-002040-BG-XX2-MRR02 Bulgaria XX2 Institutions subject to reserve requirements 2-003000-BG-XXX-MRR01 Debt securities issued Bulgaria No breakdown Institutions subject to reserve requirements Initial maturity