Which box ?
Several states do not have a state income tax. So these states will not show up in certain drop down lists. Leave boxes 15, 16, and 17 blank when you enter a W-2 for these states.
Alaska, Florida, Nevada, South Dakota, Tennessee, Texas, Washington and Wyoming
IF box 15 is blank (or is a state without an income tax), you leave boxes 15, 16, 17 all blank.
,,,,,,,,,,,,,(Unless there are $$ in box 17, then there has to be a state in box 15....and a state number next to it.)
Same for 18,19,20 if box 20 is empty...and again, unless $$ are in box 19, then there has to be a locality associated with those $$
