Line 9 on my W2 contains a sequence of numbers, letters, and dashes. It has been assigned by the company I work for, and my return is being held up for some reason. I think it may have something to do

[medovics]

I think the line 9 number, a verification code, is preventing e file.

[macuser_22]

Box 9 is optional.  You can just leave it blank.