Then this happens: you work in a locale that charges a 0.5% local tax, but you live in a locale that charges 1%. Job withholds 0.5%, and you file at home.

Your home locale gives you a credit for the working locale's 0.5%, and you still owe 0.5% to your home locale.

If the reverse percentages are true, job withholds 1%, home charges 0.5%, you file at home and get a 0.5% credit so you owe nothing to home locale.

Confused yet?