There is another point to consider: Getting 20% less money, doesn't necessarily also mean 20% less money after taxes. When I was working part-time (20h per week

There is another point to consider: Getting 20% less money, doesn't necessarily also mean 20% less money after taxes. When I was working part-time (20h per week) while studying, working full-time during summer meant this: ~90% more work (from 20h to 38.5h) but only ~60% higher salary (after taxes). So I just continued to work part-time in holidays and enjoyed summer. In my country higher salary means higher taxes, working less hours therefore means paying less taxes because of a lower salary. Taxes don't consider the number of hours you work. Although you need to consider that you also pay less e.g. into your pensions fund, some of your additional salary is "just" taxed away. When working 20h the difference for me was substantial, right now not so much. But that may be different for you.