A Delaware corporation that expects to owe nothing for the year still has to send in the first CIT-EST. The form is the Division of Revenue’s corporate tentative tax return, and the 2026 version is one page, revision 20250528.
The same sheet is used up to four times, with the Quarter box at the top set to 1, 2, 3 or 4. Delaware’s earlier name for this return was Form 1100-T. The 2022 return instructions name it in the sentence about declarations, and the 2025 instructions use the same sentence with CIT-EST.
Who declares, even at zero
The return instructions say every corporation must declare its estimated tax liability and prepay it in four installments. The declaration, voucher 1, is due even when the liability is zero and no payment goes with it. Vouchers 2 to 4 are not required for the rest of the year if the liability stays at zero, and fall due on their dates if it rises above zero in any of those quarters.
Page 1, top to bottom
The header takes the taxpayer ID, the calendar or fiscal year ending (a drop-down running from 12-31-2026 to 11-30-2027), the due date and the quarter. Below come the corporation’s name and address, then a check box to tick if a request for change form is being filed. Two payment boxes sit to the right: the balance due from line 8 of the worksheet, and the amount of this payment.
The bottom half is a perjury declaration with a signature, date, printed name, phone number and email address of the authorized signer. The sheet prints “DO NOT CUT THIS PAGE” twice, and the whole page goes in the envelope. A line above the signature tells you to keep a copy.
The worksheet, lines 1 to 8
| Line | Printed label | What goes in it |
|---|---|---|
| 1 | Estimate Delaware taxable income for the year | Your estimate for the full year |
| 2 | Corporate income tax rate | Pre-printed at 8.70% |
| 3 | Multiply line 1 by line 2 | The year’s estimated tax |
| 4 | Estimated liability for year | The base for this quarter’s share |
| 5 | Percentage due | The share for this quarter; the schedule is below |
| 6 | Multiply line 4 by line 5 | The installment before credits |
| 7 | Less credit carryover unused | Carryover not yet used |
| 8 | Subtract line 7 from line 6 | Cannot be less than zero; it is the balance due carried to the top box |
Due dates and percentages for 2026
Voucher 1 and half of the estimated liability are due by the 15th day of the fourth month of the tax year. Vouchers 2, 3 and 4 follow on the 15th of the sixth, ninth and twelfth months, at 20%, 20% and 10%. For a calendar-year corporation that makes April 15, June 15, September 15 and December 15, 2026.
A small corporation pays 25% four times instead. The 2025 return instructions define it by gross receipts and other income of no more than $26,071,000 (the figure adjusted for calendar year 2025 under 20 Del. C. § 515) in any two of the three preceding years, and they say a corporation that is not small has to prepay 80% of the current year’s liability.
A shortfall or a late payment draws 1.5% a month from that payment’s due date until it is paid. The penalty does not apply when the tentative payments made on time add up to at least 80% of the current year’s tax or 100% of the previous year’s.
Where CIT-EST shows up on the return
Line 16 of the CIT-TAX corporate return asks for the Delaware tentative tax paid on CIT-EST, and the instructions add that amounts paid with an extension request belong on the same line. The CIT-EXT extension request is itself filed with a payment of the anticipated liability.
Mailing it, or paying online instead
A check goes with the completed sheet to:
Delaware Division of Revenue
PO Box 0830
Wilmington, DE 19899-0830
That is a different box from the one printed on the CIT-VCH payment voucher (PO Box 2044). Paying by check requires the paper CIT-EST from revenue.delaware.gov. The online alternative is tax.delaware.gov: direct debit from a U.S. checking or savings account with no dollar limit and a later payment date allowed up to the due date, or a credit card for up to $10,000. The Division’s forms page also points filers to the Delaware Taxpayer Portal.
Official PDF: Form CIT-EST — Official PDF (revenuefiles.delaware.gov)
Before the sheet goes in the envelope
- Quarter, year ending and due date match the installment you are paying.
- Line 8 matches the balance due box, and the payment box matches the check.
- The declaration is signed and dated by the authorized signer.
- The page is uncut and a copy is kept.
Sources
- Delaware Division of Revenue, CIT-EST Corporate Tentative Tax Return, 2026, revision 20250528 (revenuefiles.delaware.gov)
- Delaware Division of Revenue, 2025 Corporate Income Tax Return Instructions, CIT-TAX (revenuefiles.delaware.gov)
- Delaware Division of Revenue, 2022 Corporate Income Tax Instructions (revenuefiles.delaware.gov)
- Delaware Division of Revenue, Business Tax Forms 2025-2026 (revenue.delaware.gov)