Why is asking me for box 15 it's empty

[ColeenD3]

If you have any state related entries, boxes 15-20, the program will ask for additional information. If you had state income and are required to file a return, the program will need the state and employer's ID number.

[Bri_and_Di]

My son is military. Box 15 shows MI, but the Employer's State ID Number is blank. The State wages field has his wage information, but since he's military, there's no state tax. If the W2 shows a blank field, shouldn't the field in Turbotax be blank to match? 

[TomK100]

You can try entering the Federal ID number in Box.15.