As others have said, she needs to figure their tax liablility with and without her income. Only then can she figure out if it is worth it for her to work.
It's not like they pay $0 if she doesn't work, so she obviously came out ahead. She has to do the math to figure out how much and then base her decisions on that!
It's not like they pay $0 if she doesn't work, so she obviously came out ahead. She has to do the math to figure out how much and then base her decisions on that!