Kind of an ignorant thing to be concerned about, hope she eventually gets corrected. It's...unlikely that she would be making enough money, at least from them as an artist, to need to actually pay any taxes as she'd be below the threshold (550000 yen). Unless she was also working part time, in...
Bro why are you doing that to the class rep even in an omake panel, you're gonna get stabbed by everyone else.
Like yeah she's probably going to be in the room watching on your wedding night but still