w2

Is the company located in that state? Some states require a tax return if your income is sourced in that state. What state?

the expert described a possible reason. However, only your employer can tell you for sure.  

Massachusetts

If you were an employee and did not physically work in MA then those wages would not be subject to MA tax.  Here is MA reference.  You will need to get with your employer to determine why there was MA withholding and correct that as applicable going forward.

Assuming there is no valid reason for MA withholding, you would file a non-resident return and allocate zero of the wages to MA.  Use these steps:

1. In the "My Info" section Edit your information to indicate the state(s) you lived in
2. Scroll down to "Other State Income"
3. Answer "Yes" you earned income in another state
4. Select "MA"
5. Be sure to "Continue" to set the changes
6. This will generate the MA non-resident return
7. In the "Wages and Income" section
8. Enter the form W2 information just as your form reads
9. Continue to complete any changes
10. Continue the MA non-resident interview
11. In the income section you will be able to allocate zero to MA or all to non-MA sources as applicable

MA Department of Revenue may contact you to get a supporting letter from your employer for the mistaken withholding.