Washington D.C. Filing Due Date: Business tax returns are due by March 15 — or by the 15th day of the 3rd month following the end of the taxable year (for fiscal year filers).
Extended Deadline with Washington D.C. Tax Extension: The District of Columbia offers a 6-month extension, which moves the filing deadline to September 15 (for calendar year filers).
Washington D.C. Tax Extension Form: You can apply for a DC tax extension by filing Form FR-128 by the original deadline of your return.
Washington D.C. Extension Payment Requirement: An extension of time to file is not an extension of time to pay. If you owe DC tax, it must be paid by the original due date to avoid penalties and interest. You can include your extension payment with Form FR-128, or you can pay electronically via the “eTaxpayer Service Center” (eTSC):
Washington D.C. Tax Extension Tips: If your DC tax liability exceeds $5,000 for any period, you must pay electronically.
The District of Columbia does NOT accept the Federal tax extension in place of its own extension application, Form FR-128.