Ah, I think I see the difference - for singles (class I) it gives you 43%, I mistakenly chose the married category (class III, in my mind that was the "default"

Ah, I think I see the difference - for singles (class I) it gives you 43%, I mistakenly chose the married category (class III, in my mind that was the "default" tax class - probably cause that's how I have always filed in Germany), in which case the rate is 33%.