You are mixing up some facts.

By taking your number of 120.000,- EUR salary before tax and entering it into the tax calculator of the Ministry of Finance [0], I get about the same number for the final salary. Therefore, the employee had to pay about 39% tax and social security.

The employer, however, had to pay the salary of 120.000,- to the employee and about 22% of the salary to the state and social insurance.

Apart from that, 120.000,- EUR for a developer in Vienna seems a bit too much. I would expect something between 40.000 - 65.000 on average and higher salaries in the banking / insurance sector. 120.000,- EUR is e.g. the salary of a head of unit in a big Austrian insurance company.

[0] http://onlinerechner.haude.at/bmf/brutto-netto-rechner.html