Opinion of the Advocate General — ECLI:EU:C:2021:301
Date: 2021-04-15
Language of the case: Polish
Subject matter: Social security for migrant workers
Procedure: Reference for a preliminary ruling
Origin: Poland

Summary C-866/19 — 1 
Case C-866/19 
Summary of a request for a preliminary ruling pursuant to Article 98(1) of 
the Rules of Procedure of the Court of Justice 
Date lodged: 
27 November 2019 
Referring court: 
Sąd Najwyższy (Supreme Court, Poland) 
Date of the decision to refer: 
19 September 2019 
Applicant: 
SC 
Defendant: 
Zakład Ubezpieczeń Społecznych I Oddział w Warszawie Wydział 
Realizacji Umów Międzynarodowych (Social Insurance Institution, 
Branch No 1 in Warsaw, International Agreement Department) 
  
Subject matter of the case in the main proceedings 
Proceedings in the case brought by SC against the Social Insurance Institution, 
Branch No 1 in Warsaw, International Agreement Department, concerning the 
amount of retirement pension. 
Subject matter and legal basis of the reference 
Subject matter: the interpretation of Article 52(1)(b) of Regulation (EC) 
No 883/04 of the European Parliament and of the Council of 29 April 2004 on the 
coordination of social security systems. 
Legal basis: Article 267 of the Treaty on the Functioning of the European Union. 
EN 
SUMMARY OF THE REQUEST FOR A PRELIMINARY RULING — CASE C-866/19 
 
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Question referred 
Should Article 52(1)(b) of Regulation (EC) No 883/04 of the European Parliament 
and of the Council of 29 April 2004 on the coordination of social security systems 
be interpreted as meaning that the competent institution: 
(a) takes into account, in accordance with national law, non-contribution 
periods not exceeding one third of the aggregated contribution periods completed 
under national law and under the legislations of the other Member States both for 
the purpose of determining the theoretical amount (point (i)) and the actual 
amount (point (ii)) of the benefit; or 
(b) takes into account, in accordance with national law, non-contribution 
periods not exceeding one third of the aggregated contribution periods completed 
under national law and under the legislations of the other Member States only for 
the purpose of determining the theoretical amount (point (i)) but not for the 
purpose of establishing the actual amount (point (ii)) of the benefit; or 
(c) does not take into account, either for the purpose of determining the 
theoretical amount (point (i)) or the actual amount (point (ii)) of the benefit, 
periods of insurance in another Member State when calculating the limit on non-
contribution periods under national law? 
Applicable provisions of EU law 
Regulation (EC) No 883/2004 of the European Parliament and of the Council of 
29 April 2004 on the coordination of social security systems (OJ 2004 L 166, p. 1) 
(‘Regulation 883/2004’). 
Council Regulation (EC) 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 (OJ [2006] L 392, p. 1) 
(‘Regulation 1408/71’). 
Decision No H6 of 16 December 2010 concerning the application of certain 
principles regarding the aggregation of periods under Article 6 of Regulation (EC) 
No 883/2004 on the coordination of social security systems (OJ 2011 C 45, p. 5) 
(‘Decision H6’). 
Applicable provisions of national law 
Ustawa z dnia 17 grudnia 1998 r. o emeryturach i rentach z Funduszu 
Ubezpieczeń Społecznych (Law of 17 December 1998 on Retirement and Other 
Pensions Provided by the Social Insurance Fund (Dz. U. of 2018, item 1270, as 
amended) (‘Law on Pensions’).  
ZAKŁAD UBEZPIECZEŃ SPOŁECZNYCH I ODDZIAŁ W WARSZAWIE WYDZIAŁ REALIZACJI UMÓW MIĘDZYNARODOWYCH (SOCIAL 
INSURANCE INSTITUTION, BRANCH NO 1 IN WARSAW, INTERNATIONAL AGREEMENT DEPARTMENT) 
 
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Succinct presentation of the facts and procedure in the main proceedings 
1 In its decision of 24 February 2014, Zakład Ubezpieczeń Społecznych, I Oddział 
w Warszawie (Social Insurance Institution, Branch No 1 in Warsaw, ‘the pension 
authority’) granted a retirement pension to SC (the insured person) as of 
5 November 2013 pursuant to the provisions of the Law on Pensions and 
Regulation 883/2004. 
2 In determining SC’s entitlement to a retirement pension, the pension authority 
used the following method: First, it determined the Polish contribution periods 
(104 months). Second, it included in the insurance period Polish non-contribution 
periods in an amount corresponding to one third of the Polish contribution periods 
(34 months). Third, in view of the fact that the insured person failed to reach the 
minimum insurance period on the basis of the Polish periods of insurance, the 
pension authority added to SC’s national insurance period the contribution periods 
completed in the Netherlands (269 months) in order to grant him a retirement 
pension. 
3 The insurance period thus determined (national contribution periods + national 
non-contribution periods + foreign contribution periods) was subsequently taken 
into account when calculating the theoretical amount of the benefit under 
Article 52(1)(b) of Regulation 883/2004. In turn, the actual amount of the benefit 
was calculated in the following proportion: 138 months of Polish periods of 
insurance (contribution periods plus non-contribution periods amounting to one 
third of national contribution periods) to 407 (in aggregate) Polish and foreign 
(Dutch) periods of insurance. On that basis it was calculated that out of the 
theoretical benefit of PLN 974.78, the insured person should be paid 33.9% of this 
amount, that is, PLN 335.81. 
4 The insured person appealed against the decision; in his appeal, he requested, inter 
alia, that more Polish non-contribution periods be taken into account. The Sąd 
Okręgowy w Warszawie (Regional Court in Warsaw, Poland) dismissed the 
appeal in its judgment of 19 November 2015. 
5 The insured person appealed against the judgment of the Sąd Okręgowy w 
Warszawie (Regional Court in Warsaw). In its judgment of 9 August 2017, the 
Sąd Apelacyjny w Warszawie (Court of Appeal in Warsaw, Poland), relying on 
the judgment of the Court of Justice of 3 March 2011, Tomaszewska, C-440/09, 
EU:C:2011:114 (‘the Tomaszewska judgment’), amended the contested judgment 
as follows: for the purposes of calculating the amount of the benefit to which the 
insured person is entitled, the court recognised as proven non-contribution periods 
in the amount of one third of contribution periods calculated as the sum of 
contribution periods completed in Poland and in the Netherlands.  
6 The pension authority brought an appeal on a point of law, challenging the 
judgment of the Sąd Apelacyjny w Warszawie (Court of Appeal in Warsaw) in so 
far as the court ordered the pension authority, when calculating the benefit due to 
SUMMARY OF THE REQUEST FOR A PRELIMINARY RULING — CASE C-866/19 
 
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the insured person under Article 52(1)(b) of Regulation 883/2004, to take into 
account more Polish non-contribution periods. 
Essential arguments of the parties to the main proceedings  
7 The insured person alleges that in determining the amount of the benefit to be paid 
to him, the pension authority failed to apply Article 45 of Regulation 1408/71 as 
interpreted in the Tomaszewska judgment, since it only took into account non-
contribution periods which amounted to one third of contribution periods 
completed in Poland, and according to the Tomaszewska judgment, it should have 
taken into account non-contribution periods which amounted to one third of 
aggregated contribution periods completed in Poland and in the Netherlands. 
8 However, the pension authority claims, firstly, that the interpretation of Article 45 
of Regulation 1408/71 does not apply to the present case, as in order for the 
insured person to acquire the entitlement to a pension, it proved sufficient to add 
to the Polish periods of insurance (both contribution periods and non-contribution 
periods amounting to one third of national contribution periods) the periods of 
insurance completed in another Member State. According to the pension authority, 
the Tomaszewska judgment only applies if, after using the method for calculating 
the insurance period adopted in the present case, it is found that the insured person 
has not reached the required minimum insurance period. It is only then that 
foreign contribution periods can be added to national contribution periods and the 
maximum share of domestic non-contribution periods (one third of contribution 
periods) can be calculated on the basis of aggregated (national and foreign) 
periods of insurance. Secondly, the Tomaszewska judgment concerns the 
interpretation of Article 45(1) of Regulation 1408/71 (the equivalent of which is 
Article 6 of Regulation 883/2004) rather than Article 46(2) of Regulation 1408/71 
(the equivalent of which is Article 52 of Regulation 883/2004). Thirdly, the 
application of the interpretation of Article 45(1) of Regulation No 1408/71 
adopted in the Tomaszewska judgment would result in more Polish non-
contribution periods being taken into account than under Polish law, which would 
in turn lead, on the one hand, to an increase in the contribution of the Polish social 
security system to the benefit due to the insured person and, on the other, to a 
decrease in the contribution to the funding of that benefit by the insurance system 
of another Member State to which the insured person’s contributions were paid for 
much longer than to the Polish system. Fourthly, it follows from point 2 of 
Decision H6 that the periods reported by insurance institutions in other Member 
States shall be aggregated without questioning their quality, which means that the 
Polish insurance institution cannot be obliged to take into account more national 
periods of insurance (as a result of the addition of foreign periods of insurance) 
than required by national law. 
ZAKŁAD UBEZPIECZEŃ SPOŁECZNYCH I ODDZIAŁ W WARSZAWIE WYDZIAŁ REALIZACJI UMÓW MIĘDZYNARODOWYCH (SOCIAL 
INSURANCE INSTITUTION, BRANCH NO 1 IN WARSAW, INTERNATIONAL AGREEMENT DEPARTMENT) 
 
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Brief statement of and reasons for the reference 
9 In the view of the Sąd Najwyższy (Supreme Court), Article 52(1)(b) of Regulation 
883/2004 can be interpreted in three ways, which are reflected in the question 
referred for a preliminary ruling. 
10 The first of these interpretation options is based on the Tomaszewska judgment. It 
follows from that judgment that Article 45(1) of Regulation 1408/71 must be 
interpreted as meaning that ‘in the determination of the minimum insurance period 
required by national law for the purpose of the acquisition by a migrant worker of 
entitlement to a retirement pension, the competent institution of the Member State 
concerned must take into consideration, for the purposes of determining the limit 
which non-contribution periods may not exceed in relation to contribution periods, 
as provided for by the legislation of that Member State, all insurance periods 
completed in the course of the migrant worker’s career, including those completed 
in other Member States’. The Sąd Apelacyjny w Warszawie (Court of Appeal in 
Warsaw) also used this reasoning to determine the amounts referred to in 
Article 52(1)(b) of Regulation 883/2004. 
11 The Sąd Najwyższy (Supreme Court, Poland) notes that pursuant to 
Article 52(1)(b) of Regulation 883/2004 the theoretical amount of the benefit is 
equal to the benefit which the person concerned could claim if all the periods of 
insurance which have been completed under the legislations of the other Member 
States had been completed under the legislation applied by the competent 
institution on the date of the award of the benefit. According to the Sąd 
Najwyższy (Supreme Court), this provision of Regulation 883/2004 reproduces 
the solution adopted in Article 45(1) of Regulation 1408/71 (now Article 6 of 
Regulation 883/2004). This in turn means that it can be interpreted in accordance 
with the views expressed in the Tomaszewska judgment. 
12 Article 52(1)(b) of Regulation 883/2004 clearly indicates that in calculating the 
theoretical amount of the benefit, a legal fiction must be adopted according to 
which all periods of insurance completed in other Member States are to be treated 
as if they had been completed in Poland. As Polish law uses a solution whereby 
contribution periods are counted first, and only then the limit of one third of non-
contribution periods is set, the acceptance of that legal fiction and the application 
of the reasoning adopted in the Tomaszewska judgment leads to the conclusion 
that Polish and Dutch contribution periods should be aggregated, and only then 
should one third of the contribution periods be calculated as the upper limit of 
Polish non-contribution periods. As a result, the theoretical amount of the benefit 
increases because the total insurance period taken into account in its calculation is 
longer. 
13 In the present case, this would mean extending the total insurance period from 
407 months to 445 months (104 months of contribution periods + 72 months of 
non-contribution periods applying the one third limit calculated on aggregated 
SUMMARY OF THE REQUEST FOR A PRELIMINARY RULING — CASE C-866/19 
 
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national and Dutch contribution periods amounting to 373 months + 269 Dutch 
contribution periods). 
14 If this reasoning were applied to the present case, the number of Polish non-
contribution periods which may be taken into account would increase. As a result, 
the ‘duration of the periods’ completed in Poland would also increase in relation 
to the total duration of the periods completed under Polish and Dutch legislation 
(Article 52(1)(b)(ii) of Regulation 883/2004) from 138 months (104 months of 
contribution periods + 34 months of non-contribution periods) to 176 months 
(104 months of contribution periods + 72 months of non-contribution periods). As 
a consequence, the share of the benefit paid by the Polish institution (as part of the 
pro rata benefit) would also increase from 33.9% to 39.5% (instead of 
138:407 months, it would be 176:445 months). As a result, the insured person 
would receive a higher benefit from the competent Polish institution. 
15 This interpretation of Article 52(1)(b) of Regulation 883/2004 requires the 
assumption to be made that the Tomaszewska judgment applies not only to 
acquiring the entitlement to a benefit but also to calculating its amount. This 
assumption is supported by the fact that it preserves consistency between the rules 
for determining the period of pension contributions required to acquire the 
entitlement to a benefit and the rules for determining the insurance period for the 
purposes of calculating the amount of that benefit. 
16 As it has already been accepted in the Court’s case-law that the phrase ‘as though 
they were periods completed under the legislation which it applies’ in Article 45 
of Regulation 1408/71 (now Article 6 of Regulation 883/2004) should be 
interpreted as meaning that the Polish pension authority should take into account 
Polish non-contribution periods in the maximum amount of one third of Polish 
and foreign contribution periods, then the analogous wording of Article 52(1)(b) 
of Regulation 883/2004 (‘if all the periods of insurance … had been completed 
under the legislation …’) should be interpreted in the same way, because in both 
cases a legal fiction is adopted according to which periods of insurance in other 
Member States are treated as though they were periods of insurance completed in 
Poland. 
17 This interpretation of Article 52 of Regulation 883/2004 appears to be indicated 
by the Court in paragraph 42 of its judgment of 7 December 2017, Zaniewicz-
Dybeck, C-189/16 (EU:C:2017:946). According to that judgment, it follows from 
the equivalent provision in Regulation 1408/71 that the competent institution is to 
calculate the theoretical amount of the benefit to which the person concerned is 
entitled ‘as if all the periods of work which that person completed in various 
Member States had been completed in the Member State of the competent 
institution’. In other judgments, the Court uses the phrase ‘as if the insured person 
had worked exclusively in the Member State concerned’ (judgments of 21 July 
2005, Koschitzki, C-30/04, EU:C:2005:492, paragraph 27; of 21 February 2013, 
Concepción Salgado González, C-282/11, EU:C:2013:86, paragraph 41; and of 
26 June 1980, Menzies, 793/79, EU:C:1980:172, paragraph 10). 
ZAKŁAD UBEZPIECZEŃ SPOŁECZNYCH I ODDZIAŁ W WARSZAWIE WYDZIAŁ REALIZACJI UMÓW MIĘDZYNARODOWYCH (SOCIAL 
INSURANCE INSTITUTION, BRANCH NO 1 IN WARSAW, INTERNATIONAL AGREEMENT DEPARTMENT) 
 
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18 The Court also accepts that the principle of national treatment does not mean that 
periods which have been recognised as periods of insurance in another Member 
State (for instance, periods of military service, judgment of 15 December 1993, 
Fabrizii and Others v Office national des pensions, C-113/92, EU:C:1993:930, 
paragraph 25) are excluded from the insurance period even if those periods are not 
recognised in the Member State of the competent institution. This position could 
indicate — a contrario — that more Polish non-contribution periods should be 
recognised than those resulting from national law. 
19 This interpretation of Article 52 of Regulation 883/2004 could also be supported 
by the general principle followed by the Court in interpreting the provisions of 
that regulation, according to which its provisions must be interpreted in the light 
of the objective laid down in Article 45 TFEU (ex Article 39 [48] TEC). This 
objective implies that ‘migrant workers must not suffer a reduction in the amount 
of their social security benefits as a result of having availed themselves of their 
right of free movement’ (judgment of 21 February 2013, Concepción Salgado 
González, C-282/11, EU:C:2013:86, paragraph 43, and the case-law cited therein), 
which in turn means that the application of coordination rules must not result in a 
deterioration of the migrant’s situation (judgments of 17 December 1998, 
Aristóteles Grajera Rodriguez, C-153/97, EU:C:1998:615, paragraph 17; of 
9 October 1997, Antonio Naranjo Arjona, C-31/96, C-32/96 and C-33/96, 
ECLI:EU:C:1997:475, paragraph 22; and of 9 August 1994, Reichling v INAMI, 
C-406/93, EU:C:1994:320, paragraphs 21 to 24). 
20 Further, the Supreme Court notes that the Court has already held that the purpose 
of Article 46 of Regulation 1408/71 is ‘to give a worker the maximum theoretical 
amount which he could claim if all periods of insurance had been completed in the 
State concerned’ (judgment of 21 July 2005, Koschitzki, C-30/04, EU:C:2005:492, 
paragraph 28). In order to achieve this objective, it is necessary to take into 
account non-contribution periods in relation to the sum total of contribution 
periods completed under the social security legislation of the competent institution 
as well as in other Member States (judgment of 18 February 1992, Antonietta Di 
Prinzio, C-5/91, EU:C:1992:76, paragraph 56). 
21 The second interpretation option is based on the assumption that the Tomaszewska 
judgment affects the interpretation of Article 52 of Regulation 883/2004 only 
partially. Namely, the reasoning adopted by the Court in that judgment only 
applies to the determination of the theoretical amount [Article 52(1)(b)(i) of 
Regulation 883/2004], since that provision expressly provides that the theoretical 
amount is to be calculated on the basis of the legal fiction that the insured person 
has completed all recognised periods of insurance in Poland. However, this 
reasoning does not apply to the calculation of the actual amount. This option 
requires, however, that Article 52(1)(b) of Regulation 883/2004 is interpreted as 
meaning that the proportions between the amounts paid by the competent 
institutions of two Member States must be determined by separately counting the 
periods of insurance in each of the Member States (under the rules in force in 
SUMMARY OF THE REQUEST FOR A PRELIMINARY RULING — CASE C-866/19 
 
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those Member States) in which the insured person was covered by social security, 
and by applying different rules to the theoretical and actual amounts. 
22 This interpretation of Article 52(1)(b) of Regulation 883/2004 could be supported 
by the fact that the provision refers to taking into account only the periods of 
insurance completed under the national legislation of the competent institution (in 
the present case: Polish legislation). These periods are then compared to the total 
duration of the insurance periods completed under the legislations of all the 
Member States to which the insured person was subject during his professional 
career. 
23 This interpretation might appear controversial, since it introduces different rules 
for determining the insurance period for the purposes of calculating the theoretical 
amount of the benefit and for the purposes of calculating the actual amount of the 
benefit to be paid. When calculating the theoretical amount of the benefit, national 
and foreign contribution periods will be aggregated in order to determine the 
ceiling of national non-contribution periods which may be taken into account. On 
the other hand, when calculating the actual amount of the benefit, the total 
insurance period will only comprise the periods of insurance completed under the 
legislation of each Member State, and these periods will be calculated separately. 
In the present case, for the purposes of calculating the theoretical amount, the 
insurance period would be 445 months, whereas for the purposes of calculating 
the actual amount it would be only 407 months. The theoretical amount of the 
benefit and the actual amount of the benefit paid by the Polish pension authority 
would increase, but the share of the Polish social security system in funding the 
retirement pension benefit due to the insured person would not increase, since 
instead of 39.5% under the first option, it would only amount to 33.9%. 
24 This interpretation of Article 52(1)(b) of Regulation 883/2004 could be supported 
by the view expressed in the judgment of 26 June 1980, Menzies, 793/79, 
EU:C:1980:172, paragraph 12, in which it is stated that certain periods of 
insurance are taken into account in the calculation of the theoretical benefit but 
not in the calculation of the actual benefit (see also the judgment of 3 October 
2002, Ángel Barreira Pérez, C-347/00, EU:C:2002:560, paragraph 32). 
25 Finally, the third interpretation option assumes that the Tomaszewska judgment 
only applies to the acquisition of the entitlement to a pension but not to the 
calculation of its amount. In this case, periods of insurance in another Member 
State are not taken into account at all when calculating the limit (one third of 
contribution periods) of non-contribution periods which may be taken into account 
in the calculation of the benefit. 
26 This concept, which is advocated by the pension authority, may be supported by 
the distinction made by the Court between the rules for the acquisition of pension 
entitlement and those for calculating its amount (judgment of 12 September 1996, 
Lafuente Nieto v Instituto Nacional de la Seguridad Social and Tesorería General 
de la Seguridad Social, C-251/94, EU:C:1996:319, paragraph 49) and also by 
ZAKŁAD UBEZPIECZEŃ SPOŁECZNYCH I ODDZIAŁ W WARSZAWIE WYDZIAŁ REALIZACJI UMÓW MIĘDZYNARODOWYCH (SOCIAL 
INSURANCE INSTITUTION, BRANCH NO 1 IN WARSAW, INTERNATIONAL AGREEMENT DEPARTMENT) 
 
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point 2 of Decision H6. However, both the above judgment and the decision were 
issued before the Tomaszewska judgment. 
27 The argument in favour of the third interpretation option may be that Article 6 of 
Regulation 883/2004 (corresponding to Article 45(1) of Regulation 1408/71) 
states that periods of insurance in another Member State shall be taken into 
account ‘to the extent necessary’. Since the principle is that these periods should 
be taken into account by the competent institution of a Member State only ‘to the 
extent necessary’, it could be assumed that the Tomaszewska judgment only 
applies in so far as the insured person is not entitled to a benefit on the basis of 
separately calculated contribution and non-contribution periods from each 
Member State in which he was insured. In the present case, however, the insured 
person acquired the entitlement to a pension without the need to apply the 
insurance period calculation method used in the Tomaszewska judgment, and thus 
it was not necessary to take into account the insurance period in another Member 
State for the purposes of reaching the period necessary to acquire the entitlement 
to the benefit. In this case, Article 52(1)(b) of Regulation 883/2004 may be 
interpreted as meaning that, where it is not necessary to take into account the 
insurance period from another Member State in order to acquire the entitlement to 
a pension, that insurance period is not taken into account when determining the 
duration of the national insurance period (as the sum of national contribution 
periods and national non-contribution periods up to a maximum of one third of 
aggregated national and foreign contribution periods).