Civilian Pay Earned by Active Duty Military
When an active duty servicemember also has civilian/nonmilitary wages
The Servicemembers Civil Relief Act of 2003 continued to provide that active duty military members may only be taxed on their military pay by their state of legal residence (often the same as their home of record.)
If you're not sure of your military state of legal residence, check out Filing State Income Taxes When You Are in the Military.
However, if you are an active duty servicemember and also work a nonmilitary/civilian job or are freelancing, you will probably have to file taxes in that state you are physically working in.
You'll file as a nonresident for that state. If you have to file a state return for your resident state, most of the time you can get a credit for the taxes paid on your nonresident return.