Gross 2 salary, often known as "Total employer cost", represents the actual financial amount your company must set aside to employ you and pay your salary.
Gross 2 is a wider and larger amount than Gross 1. Mathematically, it is composed of:
When you ask for a net raise of 100 EUR, the cost of that raise for the employer is not 100 EUR. Due to required payments for pension, health, and taxes to the state, that raise costs the employer significantly more (often up to 180 EUR).
Therefore, when you negotiate a new salary, the employer calculates Gross 2 in their mind to assess if you are a profitable investment.