Yes, you are correct. If the fields are blank, it means there's no withholding and it does happen often if the employer is located in a different state.

hello. my employer is in Missouri, i am in California and my box 18 is blank. but box 19 is $968. my online tax form keeps giving me an error because it says box 18 cannot be blank. when i enter 0 into box 18 i get another error saying that box 19 has to be less than 30% of box 18?

Check with your company's payroll department. 

Box 19 is the local tax withheld, so box 18, which is the income you earned for that tax to be withheld on, can't be zero. 

It seems they will need to issue you a corrected W-2. 

PLEASE CLICK HERE for more information about W-2

How do i go about filing this will i owe money back in taxes

Do i owe back in taxes if my employer didn’t put anything for lines 18-20 when there in tx an im in IN which is local tax state

@Kiyahbaby1013 Your state tax amounts are in boxes 16 and 17.    Boxes 18-20 are for city or local taxes.   Many people do not have anything in those boxes.   If they are blank on your W-2 leave them blank when you enter the information from your W-2.

When I try to leave these boxes blank (im using an online company to file), it tells me that I cannot leave them blank and will not allow me to move on.

("I'm using an online company to file")

Are  you saying that you are not using TurboTax to prepare your tax return?  If so, our ability to help you here may be limited.

In TurboTax Online, you are able to delete lines 18 through 20 of the Form W-2 if those lines are not reporting information.

In TurboTax Online, click the trashcan icon to the right of the line line to remove the lines.

Does the software that you are using allow you to remove those lines, as well?

@ValerieKerch 

I actually decided to use Turbotax and it did allow me to leave those spaces blank.