An addition or subtraction may be necessary if you sold your interest in a partnership and any increases or decreases were made to the federal basis of your partnership interest in taxable years prior to 1975, which resulted from partnership business or property located outside Wisconsin.
Where do I enter it?
Enter the additions in the Addition to Income section and subtractions in the Subtraction from Income section. Use code 55 for either entry.
What else do I need to do?
Compute the amount of any addition or subtraction due to a difference in basis on Wisconsin Schedule T. Include this form with your filing. This is not automatically completed within your account. The Schedule T cannot be attached to the return. Therefore, if you need to add this form to your return, you will need to print and mail the return.
Schedule T Instructions can be found here.