Form PRT-EXT is the Delaware Division of Revenue’s one-page request for more time to file the partnership return, Form PRT-RTN. It carries no tax computation and no payment box: a partnership, as such, owes no Delaware income tax, and the page holds only identity details, the year-end and its two dates, and a signature. This guide follows the 2025 form, Revision 20250729, which covers calendar year 2025 and fiscal years ending from January through November 2026.
Who files PRT-EXT and how it relates to a federal extension
The 2025 PRT-RTN instructions (revised 05/27/25) require a return from any business treated as a partnership for federal purposes that has income or loss, of any amount, derived from or connected with a Delaware source. A partnership with no Delaware-sourced income or loss files no return, so it has nothing to extend. Delaware sources include income from real or tangible personal property located in the state and income from a trade, business, profession or occupation carried on there.
The partners pay the tax. A nonresident partner reports their share of Delaware-sourced partnership income or loss on Form PIT-NON or on a composite return; a resident partner reports their share on Form PIT-RES. An extension for the partnership return does not move any partner’s own filing date.
The PRT-RTN instructions describe one way to get more time: submit a copy of the federal extension application on or before the due date of the partnership return, and attach a photocopy of the approved federal extension to PRT-RTN when it is filed. The approved federal extension moves the Delaware due date to the federal extended due date. Those instructions do not mention PRT-EXT. Neither document says whether PRT-EXT on its own, with no federal extension, extends the Delaware return, or whether a copy of the federal application should go in the same envelope as PRT-EXT. A partnership relying on PRT-EXT alone can confirm this with the Division: New Castle County (302) 577-8200, Kent County (302) 744-1085, Sussex County (302) 856-5358, or 1-800-292-7826 toll-free from within Delaware.
How to fill out Form PRT-EXT, box by box
The page has six areas to complete or check. The numbers below match the frames on the marked image of the official PDF.
| Area | What to enter | Notes from the form |
|---|---|---|
| 1. Taxpayer ID | The partnership’s nine-digit taxpayer ID | The fillable PDF rejects an entry of any other length with “Please enter a valid Taxpayer ID.” |
| 2. Calendar or fiscal year ending | Pick the year-end from the list | The list offers December 31, 2025 and the last day of each month from January to November 2026. Choosing one fills “Due on or before” and “Extension to”. |
| 3. Name and address | Name of partnership, street address, city, state, ZIP code | The PDF turns typed letters into capitals and accepts only a two-letter USPS state code; any other entry brings up “Invalid USPS State Abbreviation”. |
| 4. Request-for-change checkbox | Tick only if a request for change form is being filed | The 2025 partnership forms and instructions do not name that change form. An address change is reported on PRT-RTN line A. |
| 5. Signature block | Authorized signature, date, printed name of the authorized signer, phone number, email address | The signer declares under penalties of perjury that the return is true, correct and complete. The date field takes mm-dd-yyyy. |
| 6. Mailing block | Nothing to enter | Shows the PO Box 0830 address for this page. |
The form’s own reminders sit around the signature block: sign it, keep a copy, and do not cut the page. Prepare For Print and Reset are buttons on the PDF, not fields. The partnership forms list also includes PRT-VCH, the Electronic Filer Partnership Payment Voucher, which has its own amount box and is mailed to PO Box 830; its corporate equivalent is Delaware CIT-VCH.
PRT-EXT due dates for calendar 2025 and fiscal 2026 years
PRT-RTN is due by the 15th day of the third month after the end of the taxable period. The instructions give March 15 for calendar-year partnerships. For calendar 2025 the PDF fills in March 16, 2026 as the due date (March 15, 2026 was a Sunday) and September 15, 2026 as the extended date. Both had passed when this guide was checked on October 31, 2026, so the 2025 calendar-year request can no longer be filed on time.
For the fiscal year-ends in the list, these four still had a due date after October 31, 2026:
- Year ending August 31, 2026: due November 16, 2026; extension to May 17, 2027.
- Year ending September 30, 2026: due December 15, 2026; extension to June 15, 2027.
- Year ending October 31, 2026: due January 15, 2027; extension to July 15, 2027.
- Year ending November 30, 2026: due February 15, 2027; extension to August 16, 2027.
Every “Extension to” date in the PDF falls six months after the matching due date.
Late filing penalty for the partnership return
Delaware charges a partnership that fails to file PRT-RTN, or fails to furnish the information on it, $25 for each month the failure continues, multiplied by the number of people who were partners during any part of the year. The penalty runs for at most five months. A partnership with four partners that files three months late faces 4 × $25 × 3 = $300; the same partnership can owe no more than $500 for that year. The instructions add separate penalties for a false or fraudulent return, and say that copying figures from the federal return does not protect against them.
Where to get the form and where to mail PRT-EXT
The 2025 PDF is listed under “Partnership” on the Division of Revenue’s Business Tax Forms page as “PRT-EXT Delaware Partnership Return Extension”. Mail the signed, uncut page to:
Delaware Division of Revenue
PO Box 0830
Wilmington, DE 19899-0830
The return itself goes to a different box: Delaware Division of Revenue, P.O. Box 8703, Wilmington, DE 19899-8703. PRT-RTN must include a complete copy of federal Form 1065 as filed with the IRS, with all schedules other than Schedule K-1, and, when the federal extension is relied on, the photocopy of the approved federal extension.
Official PDF: Form PRT-EXT — Official PDF (revenuefiles.delaware.gov)
Questions about Delaware PRT-EXT
Does PRT-EXT need a payment?
The 2025 form has no amount field. The PRT-RTN instructions state that a partnership, as such, is not subject to tax; partners report their shares on PIT-RES, PIT-NON or a composite return.
Is an IRS extension enough for Delaware?
The 2025 PRT-RTN instructions say a copy of the federal extension application submitted by the due date extends the Delaware return to the federal extended date. A photocopy of the approved federal extension then goes with PRT-RTN.
Can a 2025 calendar-year partnership still use PRT-EXT?
The calendar 2025 request was due by March 16, 2026, and the extended date of September 15, 2026 has also passed. A PRT-RTN filed late is subject to the $25 per partner per month penalty, for up to five months.
Official sources
- Form PRT-EXT, Partnership Request for Extension, 2025 (Revision 20250729)
- Delaware Partnership Return Instructions, Form PRT-RTN, 2025 (revised 05/27/25)
- Form PRT-RTN, Partnership Return, 2025 (Revision 20251105)
- Form PRT-VCH, Electronic Filer Partnership Payment Voucher, 2025
- Business Tax Forms, Delaware Division of Revenue