If you wish to voluntarily submit documentation related to a previously filed return, on the procedures page of the aforementioned procedure in the E-Office you will find the link "Submit additional documentation" or "Make statements and/or submit documents or proof".
As with other online filings, submitting documentation requires an electronic certificate or Cl@vePIN, in this case if the filer is a private individual.
Complete the required fields for online registration and click "Add file" to include the documentation.
Some of the formats admitted as valid by the system are.doc, .gif, .png, .jpg, .pdf and zipped files .zip or. 7z. The admitted size of each of the attached files may not exceed a capacity of 64 MB. You can consult the complete list of admitted formats in the "Help" link available in each of the documentation submission forms.
It is recommended that the file to be attached is stored in the path C:\AEAT, since according to the procedure with which the submission of documentation is related, this location will be compulsory.
If you don't have the file, you can write the reason for filing in the field provided. A PDF document will be generated and incorporated into the system.
The affirmative reply to the submission of documentation will be a supporting document including all the information together with the link "View in printable format" in order to obtain the supporting document in PDF
Additionally, the CSV (Secure Verification Code) is included, which also allows the supporting document to be obtained via the "Verification of electronic documents". In addition, each file presented will have its own associated CSV