A number of answers u2022 including one from a supposed IRS employee u2022 say not tophysically attach them but just to include the W2 in the envelope.In fact the 1040 instructions say to u201cattachu201d the W2 to the front of thereturn and the Form 1040 itself u2014around midway down the lefthand side u2022 saysto u201cattachu201d Form W2 here throwing it in the envelope is not u201cattaching.u201dAnything but a staple risks having the forms become separated just likeconnecting the multiple pages of the return scheduled etc.