Delaware
State Business Tax Extension
Delaware (DE) Requires:
- Businesses to file Federal Form 7004 to request an extension with the state rather than requesting an extension using the state extension Form.
- Businesses are only required to file Form 1100-T-EXT or Form
400-EX for an extension of their state tax returns (Form 1100, 1100S, and 400) if their federal extension was rejected by
the IRS.
An Overview of Delaware State Business Income Tax Extension Forms
- Updated April 09, 2025 - 8.00 AM by Admin, ExpressExtensionTable of content
1. Does Delaware support Tax extensions for business income
tax returns?
2. What extension form does the State of Delaware require?
3. Deadline to file an extension with the State of Delaware
4. Paying balance due along with Extension
5. Mailing Address for filing Extension with the State
of Delaware
Does Delaware support tax extension for business income
tax returns?
Yes. The state of Delaware requires businesses to
file a Federal Form 7004 rather than requesting a separate state tax extension.
State Tax Extension Form can be filed only if the federal tax extension Form 7004
was rejected.
What extension form does the State of
Delaware require?
For Corporation
The businesses operating
(as C Corporation) in Delaware need to
file Form 1100-T-EXT with the state to obtain a
6-month extension of time to file their business income tax return with the state.
-
Form 1100-T-EXT - Request for
Six-Month Extension to File Delaware Corporation Income Tax Return.
For S Corporation
The businesses operating
( S-Corporation) in Delaware need to file Form 1100-P-EXT with the state to obtain a
6-month extension of time to file their business income tax return with the state.
- Form 1100-P-EXT - Request for
Six-Month Extension to File Delaware Corporation Income Tax Return.
For Partnership
The businesses operating
(as Partnership) in Delaware need to file Federal Extension with the state to obtain a 6-month extension of time to file their business income tax return with the state.
For Fiduciaries
Businesses operating (as a Fiduciary) in Delaware are required to file
Form 400-EX with the state to obtain a 6-month extension of time to file their business income tax return with the state.
- Form 400-EX - Request for 5 ½ Month Extension to File Delaware Corporation Income Tax Return.
Note: Make sure to pay any taxes due along with the extension Form to avoid penalties and interest.
What is the deadline to file Form 1100-T-EXT, Form 1100-P-EXT, Form 7004, and Form 400-EX with the State of Delaware?
Delaware Corporate Tax Extension
Delaware Corporate Tax Extension Form 1100-T-EXT is due by the 15th day of the 4th month following the end of the corporation reporting period.
For corporations operating on a calendar year, this deadline is
on April 15.
To file an extension for Form 1100, apply for an extension using Form 1100-T-EXT on or before the same date the business tax return is due.
Form 1100-T-EXT grants an automatic 6-month extension of time to file Form 1100.
Note: Make sure to pay any taxes due along with the extension Form to avoid penalties and interest.
Delaware S-Corporation Tax Extension
Delaware S- Corporation tax extension Form 1100-P-EXT is due by the 15th day of the 3rd month following the end of the corporation reporting period.
For corporations operating on a calendar year, this deadline is on March 15.
To file an extension for Form
1100-S,apply for an extension using Form 1100-P-EXT on or before the same date the business tax return
is due.
Form 1100-P-EXT grants an automatic 6-month extension of time to file Form 1100-S.
Note: Make sure to pay any taxes due along with the extension Form to avoid penalties and interest.
Delaware Partnership Tax Extension
Delaware State Partnership Tax Extension is due by the 15th day of the third month after the end of the partnership reporting period.
For businesses operating as partnerships on the calendar year, this deadline is on March 15.
To file an extension for Form 300, apply for an extension using Federal Extension Form on or before the same date the partnership tax return is due.
Extension of time to file returns may be obtained by submitting a copy of the Federal extension application on or before the due date of the partnership return. A photocopy of the approved Federal extension MUST be attached to the return when filed. The approved Federal extension will extend the due date of the Delaware return to the same date as your Federal extension
due date.
Delaware Fiduciary Tax Extensions
The Delaware Fiduciary Tax Extension Form 400-EX is due by the last day of the 4th month following the end of the fiduciary reporting period.
For Fiduciaries operating on a calendar year, this deadline is on April 30.
To apply for an extension of time to file Form 400, file Form 400-EX on or before the original deadline that the business tax return is due.
Form 400-EX grants an automatic 5 ½ month extension of time to file
Form 400.
Note: Pay any taxes due when filing the extension Form to avoid penalties
and interest.
How do I pay my balance due along with the extension Form?
You can choose to pay your balance due along with your return by using any one of the following options:
- Payment of the anticipated liability must be made with the extension request.
- EFT - Electronic Funds Transfer
(use https://revenue.delaware.gov/services/BusEFT/BusEft.shtml u to make
EFT payments) - Check or money order - Make checks payable to the Delaware Department of Revenue. Include the taxpayer’s EIN on the front of the check or money order. Include the check or money order with the extension request.
Where do I mail the Delaware extension Form 1100-T-EXT,
1100-P-EXT & 400-EX?
Mail Form 1100-T-EXT with remittance to:
Delaware Division of Revenue,P.O. Box 830,
Wilmington, DE 19899-0830.
Mail Form 1100-P-EXT with remittance to:
Delaware Division of Revenue,P.O. Box 8751,
Wilmington, DE 19899-8751.
Mail Form 400-EX with remittance to:
Division of Revenue,P.O. Box 2044,
Wilmington, Delaware 19899-2044.
Published by ExpressExtension Support, ExpressExtension
Last modified 12/07/2021 6:45:10 AM EST