Visa & residence
Fiktionsbescheinigung
A Fiktionsbescheinigung is a temporary certificate that keeps your German residence status legal while the foreigners' office processes your permit application or renewal. With a §81(4) fiction certificate, your old permit's rights, including work rights, continue unchanged.
When you apply to extend or change a residence permit before it expires, German law treats your old permit as continuing until the authority decides. The Fiktionsbescheinigung is the paper (or card) documenting this fiction. The crucial variant is §81 Abs. 4 AufenthG: your previous title and all its conditions, including work permissions, remain in force.
A different variant, §81 Abs. 3, applies to people who were staying legally without a title; it permits the stay but not automatically the work. Which paragraph is ticked on the certificate therefore matters enormously, and employers' HR departments will look at exactly that checkbox.
What it means for working students
Backlogged foreigners' offices mean many students live on a Fiktionsbescheinigung for months. With the §81(4) variant you can keep your working student job without interruption; show the certificate together with your expired permit to your employer. Apply for renewal well before expiry, since only an application filed in time triggers the fiction effect. Travel abroad is possible with a §81(4) certificate plus expired title and passport, but re-entry with §81(3) is not; check before booking flights.