Opinion of the Advocate General — ECLI:EU:C:1999:33
Date: 1999-01-28
Language of the case: Dutch
Based on: Treaty establishing the European Economic Community (1957)
Subject matter: Social security for migrant workers
Procedure: Reference for a preliminary ruling
Origin: Netherlands

Summary of the Judgment 
1. Social security for migrant workers — Legislation applicable — Workers made 
available on a temporary basis in a Member State other than that in which the 
employer is established — Legislation of the Member State of establishment — 
Condition — The employer undertaking must normally carry out its activities in the 
Member State of establishment 
(Council Regulation No 1408/71, Art. 14(l)(a» 
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SUMMARY — CASE C-202/97 
2. Social security for migrant workers — Legislation applicable — Workers made 
available on a temporary basis in a Member State other than that in which the 
employer is established — E 101 certificate issued by the competent institution of the 
Member State of establishment •— Evidentiary value for social security institutions in 
other Member States — Limits 
(Council Regulations Nos 1408/71 and 574/72, Art. 11(1) (a)) 
1. Article 14 ( l ) ( a ) of Regula t ion 
No 1408/71, in the version codified 
by Regulation No 2001/83, is to be 
interpreted as meaning that, in order to 
benefit from the advantage afforded by 
that provision (which, derogating from 
the rule that a person is to be subject to 
the legislation of the Member State on 
whose territory he is employed, allows 
the undertaking to which he is nor­
mally attached to keep him registered 
with the social security scheme of the 
Member State on whose territory it is 
established), an undertaking engaged in 
providing temporary personnel which, 
from one Member State, makes work­
ers available on a temporary basis to 
undertakings based in another Member 
State must normally carry on its activ­
ities in the first State. That requirement 
is met where the undertaking habi­
tually carries on significant activities in 
the State in which it is established. 
(see paras 21, 29, 33, 40, 45, 
operative part 1-2) 
2. Art icle l l ( l ) ( a ) of Regula t ion 
No 574/72 laying down the procedure 
for i m p l e m e n t i n g R e g u l a t i o n 
No 1408/71, in the version codified 
by Regulation No 2001/83, is to be 
interpreted as meaning that the E 101 
certificate issued by the institution 
designated by the competent authority 
of a Member State is binding on the 
social security institutions of other 
Member States in so far as it certifies 
that workers posted by an undertaking 
providing temporary personnel are 
covered by the social security system 
of the Member State in which that 
undertaking is established. However, 
where the institutions of other Member 
States raise doubts as to the correctness 
of the facts on which the certificate is 
based or as to the legal assessment of 
those facts and, consequently, as to the 
conformity of the information con­
tained in the certificate with Regula­
tion No 1408/71 and, in particular, 
with Article 14(l)(a) thereof, the issu­
ing institution must re-examine the 
grounds on which the certificate was 
issued and, where appropriate, with­
draw it. 
(see para. 59, operative part 3) 
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