The type of documents you can transmit with the T2 Attach-a-doc service is limited to a specific list of certificates and documents. This list appears on the AttachADoc worksheet in TaxCycle T2.
You cannot upload documents other than those on this worksheet. Likewise, you cannot use it to transmit documents usually submitted through a CRA My Business Account, or to file T106, T1134 and/or T1135 returns.
The documents must be in one of the following file types: pdf, doc, docx, xls, xlsx, rtf, txt, jpg, jpeg, tiff, tif, xps.