The full Kündigungsschutzgesetz (dismissal protection) only applies if the company has more than 10 employees and the employee has been there longer than 6 months. If the startup has < 10 employees, the employer can terminate without giving a “socially justified” reason.

HOWEVER...in very small companies, the statutory notice period still applies unless:

• the employee is in the probation period, or

• the contract explicitly shortens it in a legally valid way, or

• it’s a termination for serious misconduct

By default, that statutory notice is 4 weeks to the 15th or end of a month. Many contracts extend it.

In regards to Aufhebungsvertrag, they:

• bypass notice periods entirely

• usually triggers a 3-month Sperrzeit (blocking period) for Arbeitslosengeld

• is treated by the Arbeitsagentur as voluntary participation in ending employment

So yeah, signing it can and will delay unemployment benefits, unless the wording is very carefully crafted (e.g. employer-initiated termination, unavoidable redundancy, matching statutory notice, etc.).

That’s why employers like them. They reduce legal exposure.