Well they always ask to attach any supporting documents when we mail them in.  I was just wondering how to do that.  For instance, one of my clients brought me a 2019 w-2 form instead of a 2020.  The government caught it and refused his refund.  He had already received his state refund.  So I had to do an amended return with the 2020 information.  I thought I should attach the 2 w-2s to show what we were doing.