Provisional text
OPINION OF ADVOCATE GENERAL
RANTOS
delivered on 7 March 2024 (1)
Case C‑701/22
SC AA SRL
v
MFE
(Request for a preliminary ruling from the Curtea de Apel Cluj (Court of Appeal, Cluj, Romania))
(Reference for a preliminary ruling – Economic, social and territorial cohesion – Structural funds – European Regional Development Fund (ERDF) – Regulation (EC) No 1083/2006 – Article 60 – Function of the managing authority – Principle of sound financial management – Obligation to reimburse eligible expenditure – Termination of a financing contract under the ERDF on account of irregularities in its performance – Annulment of termination – Late payment – Default interest – Principles of equivalence and effectiveness – Irregularities in the performance of the financing contract – Consequences)
Introduction
1. The request for a preliminary ruling has been made in a dispute between SC AA SRL, a limited liability company governed by Romanian law (‘AA’), and the Ministerul Fondurilor Europene (Ministry of European Funds, Romania; ‘MFE’) relating to payment of default interest in relation to the late reimbursement by the MFE of eligible expenditure under a financing contract which it concluded with AA to implement a programme co-financed by the European Regional Development Fund (ERDF).
2. This Opinion focuses, in essence, on two questions. The first is the question whether the principle of sound financial management, which is referred to in Article 60 of Regulation (EC) No 1083/2006, (2) read in conjunction with the principle of equivalence, requires or precludes a legal person from being able to obtain from the competent national authority default interest in relation to the late payment of eligible expenditure in respect of European funds for the period in which an administrative act was in force which terminated the financing contract and which was subsequently annulled by the national court having jurisdiction. If the possibility of obtaining such interest is accepted, this raises the second question of whether the amount of such interest may be limited by that court on account of irregularities committed by the beneficiary in the performance of the financing contract, in the absence of financial corrections applied by the competent national authority.
Legal framework
European Union law
Regulation (EC) No 1080/2006
3. Article 7 of Regulation No 1080/2006, (3) entitled ‘Eligibility of expenditure’, is worded as follows in paragraph 1(a):
‘The following expenditure shall not be eligible for a contribution from the ERDF:
(a) interest on debt’.
Regulation No 1083/2006
4. Article 14 of Regulation No 1083/2006, entitled ‘Shared management’, provides in paragraph 1:
‘The budget of the European Union allocated to the Funds shall be implemented within the framework of shared management between the Member States and the Commission, in accordance with point (b) of Article 53 of [Regulation (EC, Euratom) No 1605/2002 (4)], with the exception of the instrument referred to in Article 36a of this Regulation and of the technical assistance referred to in Article 45 of this Regulation.
The principle of sound financial management shall be applied in accordance with Article 48(2) of [Regulation No 1605/2002].’
5. Article 60 of that regulation, entitled ‘Functions of the managing authority’, provides:
‘The managing authority shall be responsible for managing and implementing the operational programme in accordance with the principle of sound financial management and in particular for:
(a) ensuring that operations are selected for funding in accordance with the criteria applicable to the operational programme and that they comply with applicable Community and national rules for the whole of their implementation period;
(b) verifying that the co-financed products and services are delivered and that the expenditure declared by the beneficiaries for operations has actually been incurred and complies with Community and national rules; verifications on-the-spot of individual operations may be carried out on a sample basis in accordance with the detailed rules to be adopted by the Commission in accordance with the procedure referred to in Article 103(3);
…’
6. Article 70 of the regulation, entitled ‘Management and control’, stipulates:
‘1. Member States shall be responsible for the management and control of operational programmes, in particular through the following measures:
(a) ensuring that management and control systems for operational programmes are set up in accordance with Articles 58 to 62 and function effectively;
(b) preventing, detecting and correcting irregularities and recovering amounts unduly paid together with interest on late payments where appropriate. They shall notify these to the Commission and keep the Commission informed of the progress of administrative and legal proceedings.
2. When amounts unduly paid to a beneficiary cannot be recovered, the Member State shall be responsible for reimbursing the amounts lost to the general budget of the European Union, when it is established that the loss has been incurred as a result of fault or negligence on its part.
3. The implementing rules for paragraphs 1 and 2 shall be adopted by the Commission in accordance with the procedure referred to in Article 103(3).’
7. Article 80 of the regulation, entitled ‘Wholeness of payment to beneficiaries’, is worded as follows:
‘Member States shall satisfy themselves that the bodies responsible for making the payments ensure that the beneficiaries receive the total amount of the public contribution as quickly as possible and in full. No amount shall be deducted or withheld and no specific charge or other charge with equivalent effect shall be levied that would reduce these amounts for the beneficiaries.’
8. Article 98 of Regulation No 1083/2006, entitled ‘Financial corrections by Member States’, provides in paragraphs 1 and 2:
‘1. The Member States shall in the first instance bear the responsibility for investigating irregularities, acting upon evidence of any major change affecting the nature or the conditions for the implementation or control of operations or operational programmes and making the financial corrections required.
2. The Member State shall make the financial corrections required in connection with the individual or systemic irregularities detected in operations or operational programmes. The corrections made by a Member State shall consist of cancelling all or part of the public contribution to the operational programme. The Member State shall take into account the nature and gravity of the irregularities and the financial loss to the Funds.
…’
Romanian law
Law No 554/2004
9. Article 28(1) of Legea nr. 554/2004 (5) provides:
‘The provisions of the present law shall be supplemented by the provisions of the Code of Civil Procedure, in so far as they are not incompatible with the specific nature of the authority relationships between public authorities, on the one hand, and persons whose legitimate rights or interests have been prejudiced, on the other, and with the procedure governed by the present law. The compatibility of the application of the rules of the Code of Civil Procedure shall be determined by the court when it rules on the pleas.’
The Civil Code
10. Article 1535 of the Civil Code,(6) entitled ‘Default interest in the case of pecuniary obligations’, provides:
‘(1) Where a sum of money is not paid by the due date, the creditor shall be entitled to default interest from the due date until the date of payment, at the rate agreed by the parties or, failing that, at the statutory rate, without having to prove any damage. In this case, the debtor shall not be entitled to prove that the damage suffered by the creditor by reason of late payment would be less.
(2) If, before the due date, the debtor owed interest at a rate higher than the statutory rate, default interest shall be due at the rate applicable before the due date.
(3) If the rate of default interest due is not higher than the statutory rate, the creditor shall be entitled, in addition to interest at the statutory rate, to damages for reparation in full of the damage suffered’.
OG No 13/2011
11. Article 1 of OG No 13/2011 (7) is worded as follows:
‘(1) The parties shall be free to set, by agreement, an interest rate both for repayment of a loan of a sum of money and for late payment of a pecuniary obligation.
(2) Interest owed by the debtor of the obligation to pay a sum of money by a certain date, calculated for the period prior to the due date of the obligation, shall be called remunerative interest.
(3) Interest owed by the debtor of the pecuniary obligation for failure to comply with the obligation in question at the due date shall be called penalty interest.
…’
12. Article 3 of that order, as amended, reads as follows:
‘(1) The statutory remunerative interest rate shall be set at the level of the reference interest rate of the National Bank of Romania, which is the policy rate established by decision of the board of directors of the National Bank of Romania.
(2) The statutory penalty interest rate shall be set at the reference interest rate plus four percentage points.
(2a) In relations between professionals and between professionals and contracting authorities, the statutory penalty interest rate shall be set at the reference interest rate plus eight percentage points.
(3) In legal relations which do not arise from the operation of a profit-making undertaking within the meaning of Article 3(3) [of the Civil Code] … the statutory interest rate shall be determined in accordance with the provisions of paragraph 1 and paragraph 2 respectively, reduced by 20%.
…’
13. Under Article 10 of that order, ‘the provisions of Article 1535 and Articles 1538 to 1543 [of the Civil Code] … shall be applicable to penalty interest’.
OUG No 66/2011
14. Article 42(1) and (2) of OUG No 66/2011, (8) in the version applicable to the dispute in the main proceedings, provided:
‘(1) Budgetary debts arising from irregularities shall be due upon expiry of the payment deadline set in the credit instrument or within 30 days from the date of notification of that instrument.
(2) Where the debtor does not comply with the obligations provided for in the credit instrument within the prescribed period, it shall owe interest calculated by applying the rate of interest due on the outstanding balance of the amount expressed in [Romanian lei (RON)] of the budgetary debt, from the first day following the expiry of the payment deadline set in accordance with paragraph 1 until the date of extinction of the debt, unless the rules of the European Union or the international public donor provide otherwise.’
The dispute in the main proceedings, the questions referred for a preliminary ruling and the procedure before the Court
15. On 22 April 2015, the MFE, the managing authority for the ERDF Sectoral Operational Programme ‘Increase of Economic Competitiveness 2007-2013’, and AA, a limited liability company governed by Romanian law, concluded a financing contract (‘the financing contract’) within the framework of that programme for the implementation of the project entitled ‘Purchase of equipment to increase the production capacity of AA’ (‘the project at issue’). Under that contract, the MFE undertook to grant AA non-repayable financing in a maximum amount of RON 3 334 257.20 (approximately EUR 753 000) for the implementation of the project at issue. (9)
16. In order to begin the process of purchasing equipment under that project, AA took out a loan equivalent to the amount of financing with a bank to cover the expenditure eligible for reimbursement.
17. Two actions have been brought in respect of the performance of the financing contract, the first of which resulted in the reference for a preliminary ruling which is the subject of the present case.
18. The first action arose because, after the project at issue had been completed, AA submitted a claim for reimbursement of eligible expenditure, on which no action was taken, (10) resulting in additional expenditure related to the extension of the loan. (11) Consequently, on 18 April 2016, AA brought an action before the Curtea de Apel Cluj (Court of Appeal, Cluj, Romania), the referring court, seeking an order that the MFE (i) adopt a decision accepting the claim for reimbursement; (ii) reimburse the eligible expenditure in an amount equivalent to the non-repayable financial support under the financing contract; (iii) pay statutory interest on that amount from the date on which the action was brought; and (iv) in the alternative, pay damages for material loss suffered.
19. The second action arose because in the interim, on 29 August 2016, the MFE terminated the financing contract on account of certain irregularities. (12) Consequently, on 27 April 2017, AA brought an action against the MFE before the Curtea de Apel Cluj (Court of Appeal, Cluj), this time seeking annulment of the termination of the financing contract. By a judgment which became final on 10 March 2021, (13) that court upheld the action on the ground that, despite certain irregularities committed by AA in the performance of the financing contract, the termination of the contract was disproportionate given the negligible importance of the irregularities. That court considers that the MFE could have applied less onerous measures, namely financial corrections. (14)
20. Following that judgment and the subsequent payment, by the MFE, of the amount of eligible expenditure, (15) the referring court is still required to determine, in the context of the first action, solely the heads of claim relating, first, to payment of default interest on the amount paid by the MFE pursuant to that judgment and, second, to payment of damages for material loss. (16)
21. In this regard, that court asks more specifically whether EU law and, in particular, the principles of sound financial management and the protection of the financial interests of the European Union preclude national law from providing for payment, to the beneficiary of a financing contract, of default interest on eligible expenditure borne by the ERDF, which was reimbursed belatedly by the managing authority following the annulment of the termination of the financing contract at issue for the period in which that termination, subsequently annulled by a court, was in force.
22. In the absence of specific provisions in EU law or national law and given the contradictory national case-law on the subject, the referring court held that it is for national law to determine the terms and conditions applicable to interest in accordance with the principle of procedural autonomy. (17) However, it asks whether, in that situation, payment of default interest pursuant to the national rules, in accordance with the principle of equivalence, is compatible with the protection of the financial interests of the European Union, and in particular the principle of sound financial management, or whether, on the contrary, that principle requires it to apply, by analogy, the provisions of national law governing the withdrawal of the financial advantage in case of irregularities, which do not provide for payment of interest. (18) In addition, that court asks whether a national court may limit the amount of default interest potentially due in order to take account of irregularities committed by the beneficiary in the performance of the financing contract, where, as in this case, that authority did not apply any financial correction in this regard.
23. Against this background, the Curtea de Apel Cluj (Court of Appeal, Cluj) decided to stay the proceedings and to refer four questions to the Court for a preliminary ruling, the following three being considered in this targeted Opinion:
‘(1) Must the principle of sound financial management be interpreted, in conjunction with the principle of equivalence, as precluding a legal person, which operates a profit-making undertaking and is the recipient of non-repayable financing from the ERDF, from obtaining from the public authority of a Member State default interest (penalty interest) in relation to the late payment of eligible expenditure for a period in which an administrative act was in force that excluded reimbursement and which was subsequently annulled by a judicial decision?
(2) If the answer to the first question is in the negative, is the fault of the recipient of the financing established by that decision relevant to the quantification of the amount of default interest, having regard to the fact that the same public authority responsible for the management of the European funds declared, ultimately, after the adoption of that decision, all the expenditure eligible?
(3) In interpreting the principle of equivalence with regard to the point in time at which default interest is awarded to the recipient of the non-repayable financing from the ERDF, is it relevant that a rule of national law provides that, in the event of a finding of irregularity, the only consequence is that the financial benefit concerned is not granted or, as the case may be, is withdrawn (repayment of the undue amounts), to the extent to which it was granted, without receipt of interest, notwithstanding that the recipient of those amounts has enjoyed the advantage of their use up to the time of repayment, and that it is only where that repayment does not take place within the statutory time limit, that is, 30 days from the notification of the credit instrument, that the provisions of Article 42(1) and (2) of [OUG No 66/2011] permit the receipt of interest after the expiry of that time limit?’ (19)
24. Written observations have been submitted to the Court by the MFE, the Romanian and Portuguese Governments and the European Commission.
Analysis
25. By its first to third questions, which will be considered in this targeted Opinion, the referring court asks, in essence, whether AA is entitled to payment of default interest in the present case (first and third questions) and whether the amount of such interest may be limited on account of irregularities committed by that company (second question).
26. I will therefore begin by examining the first and third questions referred together and then consider the second question.
The first and third questions
27. By the first and third questions, the referring court asks, in essence, whether, in accordance with the principles of the European Union, in particular the principles of sound financial management and of equivalence, a legal person is entitled to payment of default interest in relation to the late payment of eligible expenditure in respect of EU funds for the period in which an act was in force which withdrew that advantage and which was subsequently annulled by the national court having jurisdiction.
28. In the absence of express provisions in EU law and national law, that court envisages two possible solutions:
– on the one hand (first question), payment of default interest could be justified under rules of ordinary law, (20) provided they are compatible with the principles of the protection of the financial interests of the European Union and sound financial management;
– on the other hand (third question), payment of default interest could be precluded by the application, by analogy, of specific provisions of national law governing the withdrawal of the financial advantage in case of irregularities, (21) and which provide for payment of default interest only from the expiry of the time limit for repaying amounts unduly paid. (22)
29. The MFE states in that regard that the principle of equivalence cannot justify the obligation to pay default interest in the present case, in essence on account of the situation characterised by an unequal position of the parties, (23) especially since AA had failed to fulfil its obligations, (24) and that the principle of sound financial management also cannot justify that obligation, which would cause significant damage to the budget of the Member State concerned to the benefit of the beneficiaries of the funds, without any contractual or legal basis. The MFE therefore argues in favour of the application of the provision of national law governing the withdrawal of the financial advantage in case of irregularities. (25) Similarly, the Romanian and Portuguese Governments rule out the grant of default interest, in this case, pursuant to the principle of sound financial management (26) and the principle of equivalence, in the absence of national provisions governing similar situations, (27) and maintain that the Member States enjoy broad discretion in such a situation.
30. The Commission takes the view that, in the absence of specific provisions, (28) it is for the legal order of the Member State concerned to settle the issue in accordance with the principle of procedural autonomy, having regard to the principles of equivalence and effectiveness, it being understood that payment of default interest does not breach the principle of sound financial management. (29) With regard, more specifically, to the application of the principle of equivalence, the Commission states that it is for the referring court to identify comparable procedures in national law, while stating that the provision of national law governing the withdrawal of the financial advantage in case of irregularities (30) is not relevant in this respect for a category of action which is also based on EU law.
31. I note, as a preliminary point, that the implementation of the budget of the European Union under Regulation No 1083/2006 (31) is subject to shared management within the framework of which, on the one hand, the Commission is responsible, inter alia, for planning and approving programmes and, on the other, the Member States, through their managing authorities, are responsible for managing and implementing operational programmes, (32) in particular in respect of the beneficiaries, who are entitled to receive the total amount of the public contribution as quickly as possible and in full. (33) The Member State concerned is therefore responsible for the management and control of the operational programme, in particular, preventing, detecting and correcting irregularities and recovering amounts unduly paid, together with interest on late payments where appropriate. (34)
32. More particularly, the managing authority is responsible for managing and implementing the operational programme in accordance with the principle of sound financial management. (35) Under that principle, the budget must be implemented in accordance with the principles of economy, efficiency and effectiveness, (36) which means that European structural and investment funds must be used by the Member State in line with the principles and legal requirements that underlie the EU sectoral regulations. (37)
33. However, the EU sectoral regulations, interpreted in the light of the principle of sound financial management, do not include any principle under which default interest on late reimbursement or recovery involving Member States and beneficiaries is or is not to be paid in addition to the reimbursement or recovery of the undue amount. (38) Those regulations and the principle of sound financial management simply give Member States the option to claim interest on amounts recovered in accordance with national law, without defining the nature of that interest or the procedures for obtaining it. (39)
34. In these circumstances, it is for the national legal order of each Member State to establish procedural rules for actions intended to safeguard the rights of individuals, in accordance with the principle of procedural autonomy, on condition, however, that those rules are not less favourable than those governing similar domestic situations (principle of equivalence) and that they do not make it excessively difficult or impossible in practice to exercise the rights conferred by EU law (principle of effectiveness). (40)
35. In the present case, as regards the principle of equivalence, in the first place, there is nothing in EU law, in my view, to prevent the referring court from adopting either of the two solutions envisaged in point 28 of this Opinion, it being understood that it is for that court to determine what provision would be applicable, under national law, to a similar situation. In particular, it is in this context that the referring court must assess the relevance of the rule of national law raised by it in its third question, (41) under which it is only where the repayment of an undue financial advantage does not take place within the statutory time limit that interest is due.
36. Having said that, and without prejudice to the verifications that are to be carried out by the referring court, I note that in the law of the Member States default interest is normally intended to remedy the late fulfilment of an obligation, without having a strictly ‘compensatory’ function, (42) and normally follows a letter of formal notice to the debtor from the creditor. (43) There are, however, situations in which default interest applies even in the absence of actual late payment and is essentially intended to compensate for the mere loss of enjoyment of the unlawfully paid amount. (44)
37. As regards the principle of effectiveness, in the second place, in the absence of a common approach in EU legislation or in the case-law of the European Union and the Member States, I take the view that, in principle, payment of default interest by the managing authority in the case of late reimbursement of eligible expenditure in respect of EU funds, although not explicitly provided for by EU legislation, would not impair the objectives of the applicable legislation and would not run counter to the principles and legal requirements that underlie the EU sectoral regulations, in particular the principle of sound financial management. (45)
38. Furthermore, the grant of default interest in this case could not affect the financial interests of the European Union, given that such expenditure is not eligible for reimbursement to the Member State by the Commission. (46)
39. In the light of the foregoing, I propose that the first and third questions referred for a preliminary ruling be answered to the effect that the principle of sound financial management, read in conjunction with the principle of equivalence, must be interpreted as not precluding national legislation under which the beneficiary of non-repayable financing from the ERDF may obtain from the managing authority of a Member State default interest in relation to the late payment of eligible expenditure for a period in which an administrative act was in force which excluded reimbursement of that expenditure and which was subsequently annulled by a judicial decision and that, in this respect, it is for the referring court to assess, in accordance with the principle of equivalence, the relevance of a rule of national law like that under which it is only where the repayment of an undue financial advantage does not take place within the statutory time limit that interest is due.
The second question
40. By the second question, the referring court asks, in essence, whether the amount of default interest may be limited on account of irregularities committed by the beneficiary in the performance of the financing contract, when the competent authority did not apply any financial correction in this regard.
41. The MFE and the Romanian Government claim, essentially, that since the judicial decision which annulled the termination of the financing contract also found irregularities on the part of AA in the performance of the financing contract, those irregularities would preclude payment of default interest, at least in part. According to the Commission, it is for the national court to determine whether those irregularities may be taken into consideration in the calculation of the amount of default interest under national law applicable to similar domestic disputes, having regard to the general principles of EU law, in particular the principle of proportionality.
42. In my view, in the absence of applicable rules of EU law in the present case, it is again for the national legal order of each Member State to establish procedural rules for actions intended to safeguard the rights conferred on individuals, in accordance with the principle of procedural autonomy, having regard to the principles of equivalence and effectiveness. (47) In addition, in so far as the procedure at issue in the main proceedings for the grant of funding from the budget of the European Union is a measure implementing EU law, it is subject to the general principles of EU law, which include, in particular, the principle of proportionality. (48)
43. Accordingly, first of all, it is for the referring court, in accordance with the principle of equivalence, to assess whether irregularities committed by the beneficiary must be taken into consideration in similar domestic disputes and whether the rules laid down by national law are consistent with EU law.
44. In this regard, without wishing to encroach on the assessments to be made by the referring court, I consider that a distinction should be made between the question of the possible imposition of financial corrections for breaches of contractual obligations on the part of the beneficiary, which is assessed in the light of the EU and national rules on the grant of EU funds, and the question of payment of default interest for the late allocation of funds, which is assessed in the light of the national provisions governing payment of default interest in similar situations. The referring court will therefore be required to ascertain the extent to which national law permits it to take account of irregularities committed in the implementation of the project in order to justify a refusal or reduction of default interest alone. (49)
45. As regards, second, the principle of effectiveness, it falls within the responsibility of the Member State concerned to take account of compliance with EU rules and therefore to detect and correct any irregularities by cancelling all or part of the public contribution to the operational programme, taking into account the nature and gravity of the irregularities and the financial loss to the Funds. (50)
46. In the present case, the MFE made reimbursement in full of the eligible expenditure, without making any corrections. (51) In those particular circumstances, it is for the referring court to ascertain whether and to what extent national law permits it, in the case in the main proceedings concerning the claim for default interest, to take into account, potentially of its own motion, (52) irregularities identified in the judgment delivered in the second action, also bearing in mind that the reimbursement was made by the MFE in order to comply with the final judgment delivered in the second action. (53) It is not clear whether, and to what extent, the national authority had the option of imposing financial corrections in respect of the reimbursement of the amount of eligible expenditure, given that originally it had unsuccessfully imposed a stricter measure, namely the termination of the financing contract. (54) Consequently, EU law does not preclude the referring court, in so far as it is permitted by national legislation, from reopening the question of the amount of default interest possibly due on account of irregularities identified. Otherwise, those irregularities would have no implications, to the benefit of the beneficiary.
47. As regards, lastly, the principle of proportionality, in the absence of material in the file before the Court regarding irregularities in the performance of the financing contract which might be imputable to AA, it must be stated that it is for the referring court, once its jurisdiction has been recognised in the light of the above considerations, to assess whether, should such irregularities exist in this case, they justify the cancellation or reduction of any interest due, bearing in mind that when there is a choice between several equally appropriate measures, recourse must be had, in accordance with the proportionality principle, to the least onerous. (55)
48. In these circumstances, I propose that the second question be answered to the effect that, where the beneficiary of non-repayable financing from the ERDF must obtain from the public authority of a Member State default interest in relation to the late payment of eligible expenditure for a period in which an administrative act was in force which excluded reimbursement and which was subsequently annulled by a judicial decision, it is for the national court to determine, in accordance with the principle of procedural autonomy, whether irregularities committed by the beneficiary of the financing may be taken into account in the calculation of the amount of default interest under national law applicable to similar domestic disputes, subject to compliance with the principles of equivalence and effectiveness, and the general principles of EU law, in particular the principle of proportionality.
Conclusion
49. In the light of the foregoing considerations, I propose that the Court answer the first to third questions referred for a preliminary ruling by the Curtea de Apel Cluj (Court of Appeal, Cluj, Romania) as follows:
(1) The principle of sound financial management, read in conjunction with the principle of equivalence,
must be interpreted as not precluding national legislation under which the beneficiary of non-repayable financing from the European Regional Development Fund (ERDF) may obtain from the managing authority of a Member State default interest in relation to the late payment of eligible expenditure for a period in which an administrative act was in force which excluded reimbursement of that expenditure and which was subsequently annulled by a judicial decision and that, in this respect, it is for the referring court to assess, in accordance with the principle of equivalence, the relevance of a rule of national law like that under which it is only where the repayment of an undue financial advantage does not take place within the statutory time limit that interest is due.
(2) Where the beneficiary of non-repayable financing from the ERDF must obtain from the public authority of a Member State default interest in relation to the late payment of eligible expenditure for a period in which an administrative act was in force which excluded reimbursement and which was subsequently annulled by a judicial decision, it is for the national court to determine, in accordance with the principle of procedural autonomy, whether irregularities committed by the beneficiary of the financing may be taken into account in the calculation of the amount of default interest under national law applied to similar domestic disputes, subject to compliance with the principles of equivalence and effectiveness, and the general principles of EU law, in particular the principle of proportionality.