1 By judgment of 5 May 1992 received at the Court on 14 May 1992, the Tribunal du Travail (Labour Tribunal), Brussels, referred to the Court for a preliminary ruling under Article 177 of the EEC Treaty a question on the interpretation of Article 51 of Council Regulation (EEC) No 1408/71 of 14 June 1971 on the application of social security schemes to employed persons, to self-employed persons and to members of their families moving within the Community, in the version consolidated by Council Regulation (EEC) No 2001/83 of 2 June 1983 (OJ 1983 L 230, p. 6).
2 The questions arose in proceedings between Mr Fioravante Luigi Bogana, the plaintiff in the main proceedings, and Union Nationale des Mutualités Socialistes (hereinafter "UNMS"), a Belgian institution responsible for the payment of benefits, and Institut National d' Assurance Maladie-Invalidité (hereinafter "INAMI"), the Belgian institution responsible for the grant of invalidity benefits, defendants in the main proceedings.
3 It is apparent from the documents before the Court that Mr Bogana, an Italian national, worked as an employed person in Italy and in Belgium. When he became incapacitated for work he was granted in both States entitlement to receive invalidity benefits with effect from 1 November 1981.
4 The Italian invalidity benefit was calculated in accordance with the rules on aggregation and apportionment laid down in Article 46(2) of Regulation No 1408/71.
5 The Belgian invalidity benefit was determined in accordance with the provisions of national law. In view of the rules against overlapping set out in Article 76c(2) of the Belgian Law of 9 August 1963 establishing and organizing a scheme of compulsory sickness and invalidity insurance, in the version laid down by Royal Degree No 19 of 14 December 1978, the benefit paid to Mr Bogana by the competent Belgian institution was fixed at an amount equal to that of the full Belgian benefit, less the apportioned Italian benefit.
6 In view of the rule against overlapping set out in Article 46(3) of Regulation No 1408/71, if the amount of the benefit had been determined in accordance with the calculation rules set out in that article, it would have been equal to the amount of benefit determined in accordance with the rules of national law alone.
7 The Belgian invalidity benefit was successively adjusted in order to take account of changes in the Italian benefit in accordance with the provisions of Article 241a(2)(a) and (b) of the Royal Decree of 4 November 1963 implementing the Law of 9 August 1963, in the version laid down by the Royal Decree of 30 July 1981.
8 According to the provisions of that article, the calculation of the amount of benefit paid under Article 76c(2) of the Law of 9 August 1963 is to be revised: "(a) where the benefit [granted by foreign law] ... changes by 2% in relation to the amount taken into account on the occasion of the initial or preceding calculation; the new calculation shall be made at the exchange rate ruling in the quarter in which the day on which the change in the benefit occurred ... ; (b) where the average exchange rate for the foreign currency changes by 2% in relation to the exchange rate taken into account on the occasion of the initial or preceding calculation, the revision shall be carried out with effect from the first day of the quarter during which the exchange rate which has changed by 2% is applicable; ...".
9 In the course of a recalculation operation, UNMS found that the change in the Italian pension paid to Mr Bogana had not been taken into account as it should have been, and that the provisions of Article 241a(2)(a) and (b) of the Royal Decree of 4 November 1963, cited above, had not been correctly applied to him. It consequently claimed from Mr Bogana the sums of BFR 4 572 and BFR 39 093, which it considered he had been unduly paid during the period from 1 January 1987 to 28 February 1991.
10 Mr Bogana brought an action against those decisions in the Tribunal du Travail, Brussels, on the ground that the application of the provisions of Article 241a(2)(a) and (b) of the Royal Decree of 4 November 1963, cited above, was contrary to the provisions of Article 51 of Regulation No 1408/71.
11 The Tribunal du Travail, Brussels, took the view that the outcome of the proceedings depended on the interpretation of Community law and decided, pursuant to Article 177 of the EEC Treaty, to refer the following question to the Court of Justice: "Where the comparative calculation of a benefit made on the basis of national legislation (Article 76a(2) of the Law of 9 August 1963) and of Article 46(3) of Regulation (EEC) No 1408/71 produces the same result, must that benefit ° after the date on which entitlement to it has been acquired ° be adjusted in accordance with Article 51 of Regulation (EEC) No 1408/71 or in accordance with a provision of national law (Article 241a of the Royal Decree of 4 November 1963) which provides for the benefit due under national law to be recalculated so as to reflect changes in the foreign benefit which are associated in particular with fluctuations in average exchange rates and economic developments (equalization)?"
12 Reference is made to the Report for the Hearing for a fuller account of the facts of the main proceedings, the procedure and the written observations submitted to the Court, which are mentioned or discussed hereinafter only in so far as is necessary for the reasoning of the Court.
13 By means of the question submitted to the Court for a preliminary ruling, the national court asks whether an invalidity benefit paid by a Member State to a migrant worker, the amount of which, calculated under its national law alone, including the national provisions against overlapping, is equal to the amount determined under the rules of Article 46 of Regulation No 1408/71, including the rule against overlapping set out in Article 46(3), must be adjusted in accordance with the provisions of Article 51 of Regulation No 1408/71 or, on the contrary, in accordance with the provisions of national law where they provide for a recalculation of the national benefit in order to take account of changes in a benefit paid by another Member State in connection in particular with changes in average exchange rates or with the general evolution of the economic and social situation in that State.
14 Mr Bogana and the Commission suggest that the Court' s reply should be that the provisions of Article 51 of Regulation No 1408/71 should be applied. They argue that a benefit such as the one at issue in the main proceedings is to be determined in accordance with Article 46 of Regulation No 1408/71, and that the provisions of Article 51 of that regulation are consequently applicable to it. In their view, those provisions preclude any fresh calculation intended to take account of revalorizations of a foreign benefit of the same kind, other than revalorizations relating to any change in the individual situation of the person concerned.
15 INAMI suggests for its part that the Court should reply that the provisions of national law mentioned in the preliminary question should be applied. According to that institution, in the event that the amount of the benefit, determined in accordance with the rules of national law, is equal to the amount determined in accordance with the rules of Article 46 of Regulation No 1408/71, the application of the rules of national law must in fact be regarded as being more favourable than the application of Community law and consequently national law must be applied in its entirety, that is to say, including its rules against overlapping, which include, in the case at issue in the main proceedings, Article 241a of the Royal Decree of 4 November 1963, cited above.
16 INAMI' s argument cannot be accepted.
17 As the Court has consistently held (see, mutatis mutandis, the judgment in Joined Cases C-90/91 and C-91/91 Di Crescenzo and Casagrande [1992] ECR I-3851, paragraph 17), in order to calculate the amount of an invalidity benefit due under Community law to a worker who has been subject to the legislation of two or more Member States, the competent institution in each of those States must effect a comparison between the amount due under its national legislation alone, including the rules against overlapping, and the amount due under Article 46 of Regulation No 1408/71, including the rule against overlapping set out in Article 46(3). For the purposes of the payment of the benefit, the worker must benefit by whichever of the two sets of rules is more favourable to him.
18 Accordingly, even if the application of the national legislation alone, including its rules against overlapping, achieves a result which is as favourable or more favourable to the migrant worker than the result obtained by applying the rules of Article 46 of Regulation No 1408/71, including the rule against overlapping set out in Article 46(3), the amount of the invalidity benefit paid to that worker is in fact to be determined, as, moreover, INAMI stated in its observations to the Court, in accordance with Article 46 of Regulation No 1408/71.
19 Consequently, the provisions of Article 51 of Regulation No 1408/71, which, according to their very wording, relate to the revalorization and recalculation of benefits "determined under Article 46", are applicable to such benefits.
20 As the Court has consistently held (see, in particular, the judgment in Case C-93/90 Cassamali v Office National des Pensions [1991] ECR I-1401), the provisions of Article 51 must be interpreted, in order to reduce the administrative burden which a fresh examination of the worker' s situation following every alteration of benefits received would represent, as precluding a recalculation of a benefit determined in accordance with the rules of Article 46 of Regulation No 1408/71, in order to take account of revalorizations of a benefit of the same nature paid by another Member State when the revalorizations resulted from events other than those mentioned in Article 51(2), that is to say, other than a change in the worker' s personal circumstances or in the rules for calculating the benefits.
21 Consequently, provisions such as those set out in Article 241a(2)(a) and (b) of the Royal Decree of 4 November 1963 which, even though they have the effect of securing continuing compliance with the ceiling laid down by the national provisions against overlapping ° in this case Article 76c(2) of the Law of 9 August 1963 °, are not involved in the initial calculation of the invalidity benefit, but determine the circumstances in which a fresh calculation should be made of the benefit subject to the ceiling and the exchange rate applicable to the foreign benefit for the purposes of that fresh calculation, cannot be applied to a benefit which has already been paid, such as the benefit at issue in the main proceedings, without disregarding the provisions of Article 51 of Regulation No 1408/71.
22 It must therefore be stated in reply to the question submitted by the national court for a preliminary ruling that an invalidity benefit provided by a Member State to a migrant worker and paid on the basis of Articles 40 and 46 of Regulation No 1408/71, the amount of which, when calculated under the rules of national law, including its provisions against overlapping, is equal to the amount calculated under the rules laid down in Article 46 of that regulation, including the rule against overlapping contained in Article 46(3), must be adjusted in accordance with Article 51 of that regulation and not in accordance with the provisions of national law, where the latter provide for a recalculation of the national benefit in order to take account of variations in a benefit accorded by another Member State which are attributable in particular to fluctuations in average exchange rates or the general evolution of the economic and social situation in that State.