The amount of fries taken by your female significant other, after you've already asked her if she was hungry but she insisted she didn't want anything.
Boyfriend: "Babe, stop eating my fries, you said you didn't want any!"
Girlfriend: "Girlfriend tax; I'm not going to eat all of it!"
Girlfriend: "Girlfriend tax; I'm not going to eat all of it!"
by itsonlyaword January 20, 2016
Liberally interpreted as the price you have to pay for having a girlfriend: taking her out, buying her things, paying for incidentals. Can also refer to the non-monetary price: time, missed opportunities with other women, real/feigned emotional support.
by Paralytic August 4, 2010
Obligation to spend twice as much to take your significant other to an event you would have gone to without them.
"Nickelback tickets for a hundred bucks, bro!"
"Two hundred bucks for me, after the girlfriend tax, bro."
"That sucks, bro."
"Would having sex with me make you feel better, bro?"
"Two hundred bucks for me, after the girlfriend tax, bro."
"That sucks, bro."
"Would having sex with me make you feel better, bro?"
by dwaynetrobinson April 17, 2015