These are the reasons PA requires you to submit your forms W2: Since you have a letter, make a copy of the letter and attach the requested W2's.
When to Submit Form(s) W-2
Submit an actual state copy or a legible photocopy of each state
copy of Form W-2 (keep the original for your records) and a written
explanation if:
1. The PA compensation you enter on Line 1a of your PA-40 is
not the same as Box 16 on your Form W-2 (you believe that
the PA compensation or withholding is incorrect).
2. Your employer gave you a handwritten Form W-2.
3. Your employer reported an incorrect amount on your Form W-2.
You must also submit a written statement from your employer.
4. Your employer withheld PA income tax from your wages at a
rate that is more than the 2015 tax rate of 3.07 percent.
5. You are a resident of a reciprocal compensation agreement
state and your employer withheld PA income tax.
6. The Medicare wages in Box 5 on your Form W-2 are greater
than your PA wages in Box 16. In this case, complete and
include with your return the PA-40 W-2 Reconciliation Worksheet.
To obtain the worksheet, use one of the Forms Ordering
Services on Page 2.
7. You are a PA resident working in another state or country and
did not have PA income tax withheld by your employer.
8. You have a distribution from a nonqualified deferred compensation
plan included in Box 1 of your Form W-2.
9. Your Form W-2 shows income earned or tax withheld for
another state.