File an amended DC return if your DC tax liability for a prior open tax year (usually 3 years from date of filing) has changed on the D-40 return for the tax year you are amending. To file an amended return for the current year, complete another 20XX DC Individual Income Tax Return and fill in the "amended return" oval on the form. Attach a list with explanations of the changes covered by your amended return.
If you are filing an amended return for a prior year, attach a copy of the original and any amended returns filed for that tax year. You can download forms from MyTax.DC.gov or call 202-442-6546 to request forms by mail.
If the IRS adjusts your individual federal tax return, you must file an amended DC return within 90 days of receiving notice of the federal adjustment. Attach a copy of the adjusted federal return and/or determination letter.