DOR Taxation web site

E-Filer Attachments in Revenue Online

When Colorado income tax returns are filed electronically through Federal/State Electronic Filing (FSEF) or through Revenue Online, supporting documentation must be submitted to prove eligiblity for credits claimed. Scanning. saving and uploading an electronic copy of the documentation through Revenue Online is the preferred method of submitting these documents because the copy will be in the taxpayer’s account and the department will not need to ask for an additional copy later. The alternative method is to send the documentation by mail with the form DR 1778 "E-Filer Attachment Form." The DR 1778 serves as a kind of "cover letter" for the documents when they arrive at the department by mail.


If returns are filed on paper, the documentation may be attached to the paper income tax return. This method is not recommended because there is the chance the documentation will become separated from the paper return and the department will need to request it again, which delays processing the income tax filing.


Using Revenue Online ensures the documentation is immediately available to the department in the taxpayer’s account while we are reviewing the tax credit claims.


How to Submit an E-Filer Attachment in Revenue Online


E-Filer Attachments (what had previously been done exclusively with the DR 1778 E-Filer Attachment paper form), may be uploaded into Revenue Online without logging into a taxpayer’s income tax account.

  1. Go to Revenue Online.
  2. Click the blue E-Filer Attachment link.
  3. Follow the steps to enter the Taxpayer Information, Account Type and ID Type.
  4. Enter spouse information (if applicable) and mailing address.
  5. Click OK.
  6. Enter the tax year/period, income tax type (individual, corporate or partnership).
  7. From the list of documents, check the box(es) to indicate the form(s) you are attaching. This list is a duplicate of the list of documents on the DR 1778 paper E-Filer Attachment Form.
  8. Click OK.
  9. Click on the Step 3. Attach Documents link or, click on the Attachments Add link on the far left side of the screen.
  10. Enter your own description of the attachment you are submitting.
  11. Click the Browse button to find the electronic file you created, saved and now will submit.
  12. Click the Save button to attach the document. The document will be listed in the Attachments Add box on the far left side of the screen. You may remove it by clicking the red x next to the document or you may continue adding more attachments if applicable.
  13. When you have added all your attachments for this taxpayer, click the blue Submit button. You will see a confirmation message on the screen that reads: Your request for E-Filer Attachments has been sent to the Department of Revenue.
  14. The document(s) will be added to the taxpayer’s account (internal DOR system) the next business day. Because you do not need to be logged into the taxpayer’s Revenue Online account to submit an E-Filer Attachment, the request will not be shown in the taxpayer’s Revenue Online account when they or you log into the account.