As a side note, when people say "percentage of your salary" are they referring to pre or post tax? This is never clear to me and I wish people would state it explicitly.
I always do my calculations with the net amount. I don't see why you'd want to include a portion you're definitely going to lose unless you're trying to make the figures work…
Also, I don't like to include bonuses unless they're actually guaranteed.
I agree that it should be post tax, but nobody uses post-tax figures when stating how much money they make so it's often not clear which "15% of income" they are referring to.
