§ 4 Requirement for a residence title
(1) In order to enter and stay in the Federal territory, foreigners shall require a residence title, in the absence of any provisions to the contrary in the law of the European Union or a statutory instrument and except where a right of residence exists as a result of the agreement of 12 September 1963 establishing an association between the European Economic Community and Turkey (Federal Law Gazette 1964 II, p. 509) (EEC/Turkey Association Agreement). The residence titles are granted in the form of
1. a visa (Section 6),
2. a residence permit (Section 7),
2a. a EU Blue Card (§ 19a)
3. a settlement permit (Section 9) or
4. an EC long-term residence permit (Section 9a).
The law regulation applying for the residence permit does also rule for the EU blue card, provided that by law or statutory order nothing else is determined.
(2) A residence title shall entitle the holder to pursue an economic activity insofar as this is laid down in this Act or the residence title expressly permits pursuit of an economic activity. Every residence title must indicate whether the pursuit of an economic activity is permitted. A foreigner who is not in possession of a residence permit for the purpose of employment can only be permitted to take up employment if the Federal Employment Agency has granted its approval or a statutory instrument stipulates that taking up the employment concerned is permissible without the approval of the Federal Employment Agency. Any restrictions imposed by the Federal Employment Agency in granting approval are to be specified in the residence title.
(3) Foreigners may only pursue an economic activity if the residence title so allows. Foreigners may only be employed or commissioned to perform other paid work or services if they possess such a residence title. This restriction shall not apply if the foreigner is permitted by virtue of an inter-governmental agreement, a law or a statutory instrument to pursue an economic activity without requiring due authorisation via a residence title. Anyone employing a foreigner or commissioning a foreigner on a sustained basis to perform paid work or services for gain in the Federal territory must ascertain whether the conditions pursuant to sentence 2 or sentence 3 apply.