I am a resident of IL, but worked in MA. Why do I owe IL state taxes? How come my MA state taxes do not cover my IL taxes?

[JotikaT2]

Each state operates independently.  Therefore, your withholdings in Massachusetts cannot be used to offset your Illinois tax.

You must file a return in Massachusetts as a nonresident if you had annual gross income of more than $8,000.  

Since you are an Illinois resident, you will need to file a return in Illinois.  But since you have income that is being taxed in Massachusetts(MA) and Illinois, you can claim a credit in Illinois for the taxes paid on the same income earned in MA.

You can confirm your input in TurboTax to ensure you are only taxed one time on the same income as follows:

1. On the black panel on the left, select "My Info" 
2. Select "Edit" to the right of your name. 
3. Scroll down the page and review the answers to your questions. 
4. Ensure your answers to the state you lived in and any other state questions are answered correctly. 
5. Pay special attention to the line at the bottom which asks if you earned money in another state.  Confirm this entry is completed for the job which is located in Massachusetts. 

Once you enter this information, you should go back into the W-2 input under income. 

Select Edit for this W-2 and scroll down to box 15, State & Local Taxes.  Confirm your input here matches your W-2 statement.

Then go back into the state returns starting with the nonresident MA return first.  Proceed through the questions and answer accordingly.

Then go into the Illinois resident state interview section and verify the questions are answered there as well.   To claim the credit for taxes paid to MA, you will need to verify your input in the Illinois return under the credit section.

1. Select "Taxes Paid to Another State" 
2. Answer the questions until you reach "Other State" 
3. Here you will select the nonresident state where you paid taxes under "Other State" 
4. Select Continue after entering the state name.  
5. You will then be prompted to enter the portion of income taxed by the other state 
6. On the next screen, enter the amount of tax from the Other State
7. (Sometimes this amount will pull through from your nonresident return so you may not need to enter the amount.)