If you make 140400 a year and are getting 2 weeks of vacation. You are making $2700 a week. If you took another week off of unpaid time off. You will lose $2700 for that year.

If they gave you an extra week of vacation. Your taxes wouldn’t change. If instead they gave you an extra $2700 in salary and you took a week off of unpaid time off, you have to pay 24% in Federal taxes on that income + 1.45% in Medicare (you are already over the social security maximum).

You would need to make $3621 more just to start breaking even ($2700/(1 - .24 - .0145)). But even then you are paying taxes on the extra 3621-2700. I’m sure there is some formula to break even but I would just ask for an extra $4000 and call it a day.