Colorado E-Filer Attachment Form

E-Filer Attachment Form
DR 1778 E-Filer Attachment Form
DR 1778 (07/24/25)
COLORADO DEPARTMENT OF REVENUE
Denver CO 80261-0006
Tax.Colorado.gov

*DO=NOT=SEND*

E-Filer Attachment Form
Instructions for DR 1778
This form should be used if you filed a tax return electronically and were not able to attach the
required documents and forms with your return. The Department strongly recommends that you
submit these documents using the e-Filer Attachment option at Colorado.gov/RevenueOnline,
which eliminates the requirement to mail this form. Failure to timely submit required documentation
will result in denial of the related credit. Revenue Online E-Filer Attachment provides you with a
confirmation number and will be available to the Department immediately.
Otherwise, complete this form, package it with your documentation and mail to the Department. Using
this form can extend return processing time up to 6 weeks.
Mail to:
Colorado Department of Revenue
Denver, CO 80261-0006
You must resubmit your supporting documentation if you file an amended return. Do not return
this form in lieu of a payment form or if you are filing a paper return. This form is only
required if your taxes were e-filed and your software or preparer was unable to attach the
required documentation electronically.

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DR 1778 (07/24/25)
COLORADO DEPARTMENT OF REVENUE
Denver CO 80261-0006
Tax.Colorado.gov
Page 1 of 1

*251778==19999*

E-Filer Attachment Form
For Tax Year (MM/DD/YY)

or Fiscal Year beginning (MM/DD/YY)

Income Tax Type
Individual
(DR 0104)

Please print or type

C-Corporation
(DR 0112)

Partnership/S-Corp
(DR 0106)

Fiduciary
(DR 0105)

Exempt Entity
(DR 0990)

Taxpayer’s Last Name or Business Name

Taxpayer’s First Name

Middle Initial

Spouse’s Last Name (if applicable)

Spouse’s First Name

Middle Initial

Taxpayer’s SSN or ITIN

Spouse’s SSN or ITIN (if applicable)

FEIN

Mailing Address

City

State

ZIP

Complete the fields above to ensure your documents will be routed to the correct account. Mail this completed
cover sheet with any required documents such as: supplemental schedules your software does not support;
copies of credit certificates, credit letters, or receipts; or other support documentation you wish to provide.
Note: Providing information using this form does not initiate a review of your account. You must send
correspondence, send us a web message using Revenue Online, or contact our service center or call center to
initiate a review.
Signature of Taxpayer or Preparer

Date (MM/DD/YY)

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