Opinion of the Advocate General — ECLI:EU:C:1998:571
Date: 1998-11-26
Language of the case: French
Based on: Treaty establishing the European Economic Community (1957)
Subject matter: Social security for migrant workers
Procedure: Reference for a preliminary ruling
Origin: Belgium

Summary of the Judgment 
1. Social security for migrant workers — Work for the purposes of Article 14a(1)(a) of 
Regulation No 1408/71 — Meaning 
(Council Regulation No 1408/71, Art. 14a(1)(a)) 
2. Social security for migrant workers — Legislation applicable — Self-employed worker 
going to work in another Member State — E 101 certificate issued by the competent 
institution of the Member State of origin — Probative value in relation to the 
competent institution of the other Member State — Limits — Retroactive effect of the 
certificate — Admissibility 
(Council Regulation No 1408/71, Art. 14a(1)(a); Council Regulation No 574/72, 
Art. 11a) 
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SUMMARY — CASE C-178/97 
1. The term 'work' in Article 14a(1)(a) of 
Regulation No 1408/71, amended and 
updated by Regulation No 2001/83, 
and subsequently by Regulation 
No 3811/86, which provides that a 
person normally self-employed in the 
territory of a Member State and who 
performs work in the territory of 
another Member State shall continue 
to be subject to the legislation of the 
first Member State, provided the antici­
pated duration of the work does not 
exceed 12 months, covers any perfor­
mance of work, whether in an 
employed or self-employed capacity. 
That interpretation arises, first, from 
the wording of the provision in ques­
tion, the word 'work' ordinarily having 
a general meaning designating without 
distinction performance of work in 
either an employed or a self-employed 
capacity. It is, moreover, confirmed by 
the circumstances in which the provi­
sion was adopted, the Council having 
preferred the term 'work' to that of 
'provision of services' which had been 
proposed by the Commission so as to 
restrict its application exclusively to 
cases where work is performed in a 
self-employed capacity in the territory 
of another Member State. 
(see paras 16, 21, 23, 28, 
operative part 1) 
2. So long as it has not been withdrawn or 
declared invalid, an E 101 certificate, 
issued in accordance with Article 11a 
of Regulation No 574/72, stating that 
the self-employed person concerned 
remains subject to the legislation of 
his Member State of origin throughout 
a given period in which he carries out a 
work assignment in the territory of 
another Member State, is binding both 
on the competent institution of the 
Member State to which a self-
employed person goes in order to carry 
out a work assignment and the person 
who calls upon the services of that 
worker. 
However, it is incumbent on the com­
petent institution of the Member State 
which issued that certificate to recon­
sider whether it was properly issued 
and, if appropriate, to withdraw the 
certificate if the competent institution 
of the Member State in which the self-
employed person carries out a work 
assignment expresses doubts as to the 
correctness of the facts on which the 
certificate is based and, consequently, 
of the information contained therein, in 
particular because the information 
does not correspond to the require­
ments of Article 14a(1)(a) of Regula­
tion No 1408/71. 
There is nothing to prevent the E 101 
certificate from producing retroactive 
effects, according to the circumstances. 
(see paras 43, 48, 53-54, 57, 
operative part 2-3) 
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