CMP-EXT: Composite Return Extension (2025)
Delaware · Delaware Division of Revenue · Used for tax years 2025
Form CMP-EXT requests an automatic extension until October 15, 2026 to file a 2025 Delaware Composite Income Tax Return. It reports expected income tax liability, estimated tax payments, other payments and credits, and the balance due to be paid in full.
Who files this form
Form CMP-EXT is used to request an automatic extension of time to file a Delaware Composite Income Tax Return for tax year 2025.
When it's due
- Tax year 2025 extension application: Must be filed by April 30, 2026.
- Tax year 2025 extended return deadline: The form requests an automatic extension until October 15, 2026.
What you'll need
Have the following information ready to complete the form:
- Business name, street address, city, state, ZIP code, and Employer Identification Number.
- Expected total income tax liability for tax year 2025.
- Estimated tax payments, including prior-year overpayments allowed as a credit.
- Other payments and credits.
- The signing officer’s title, signature, and date, plus an email address and phone number.
How to file
- Enter the business information and tax year.
- Enter expected total income tax liability on line 1, estimated tax payments on line 2, and other payments and credits on line 3.
- Add lines 2 and 3 and enter the total on line 4.
- Subtract line 4 from line 1 and enter the balance due on line 5. The form directs you to pay the balance in full.
- Have an officer sign and date the form, and complete the title and contact information. Keep a copy for your records.
Mail the completed form with remittance payable to:
Delaware Division of Revenue
PO Box 830
Wilmington, DE 19899-0830
Common mistakes
- Forgetting to sign: The form reminds you to sign before filing.
- Not keeping a copy: Keep a copy for your records.
- Cutting the page: The form explicitly says not to cut the page.
Questions people ask
What does CMP-EXT request?
It requests an automatic extension until October 15, 2026, to file the Delaware Composite Income Tax Return for tax year 2025.
Where do I include prior-year overpayments allowed as a credit?
Include them with estimated tax payments on line 2.
How do I calculate the balance due?
Add lines 2 and 3 to get line 4. Then subtract line 4 from line 1 to get the balance due on line 5, which the form directs you to pay in full.
Who signs the form?
The signature area calls for an officer’s signature, date, and title. It also asks for an email address and phone number.