What state are you in?
If Ohio, you have to file two SD returns, SD-A to pay full tax and SD-B to get a full refund. Talk to you employer, they should not be withholding SDIT for SD-B. Unlike Ohio city income tax, you do not pay tax to the SD you work in. You only pay SDIT to your residence SD.
Verify that what you think is SD-B tax isn't really city tax for the city your employer is located in. You don't have to file a work city tax return, but they are allowed to withhold city tax (but not SD income tax).
