Form W-RA is required to be mailed to the Wisconsin Department of Revenue, along with supporting documentation, when you're claiming certain credits or other items on your e-filed return.
Per the Wisconsin Instructions for Form W-RA Required Attachments for Electronic Filing, on page 2:
Use Form W-RA to submit supporting documentation when you electronically file an income or franchise tax return and claim any of the credits or items listed. Many of the above items require documentation from the WEDC. Legislators making the special section 162(h) election must mail the Model Form to the department when using electronic filing software that does not submit the Model Form as part of the electronic return.
Paper clip your attachments to Form W-RA. Refunds can be processed faster if you use paper clips instead of staples.
CAUTION Use Form W-RA only to submit supporting documentation required for the box(es) checked. Do not submit other correspondence or appeals or a paper copy of your tax return or homestead credit claim with Form W-RA.
Form W-RA and required attachments must be mailed to the department within 48 hours of receipt of your Wisconsin acknowledgment. Refunds may not complete processing until Form W-RA and attachments have been received.
Note Individuals and tax practitioners filing on behalf of individuals required to send the Form W-RA attachments to the department may transmit this data in an electronic file over the internet. To submit Form W-RA attachments electronically, go to https://tap.revenue.wi.gov/WRA/.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.