It depends -
Yes - If you are a DC resident and need to mail in your DC state income tax return, then you will need to include copies of all W-2s and 1099s regardless of where the income was earned. (Just photocopy the W-2 or 1099 that you will not be able to get an additional copy of and send in the photocopy.)
No - If you are not a resident of DC, then you will not need to file a DC state income tax return. Instead you would just include your DC sourced income as part of your total income being reported in your permanent state of residence.
You are not required
to file a DC return if you are a nonresident of DC unless you are claiming a
refund of DC taxes withheld or DC estimated taxes paid. Use Form D-40B,
Non-Resident Request for Refund (available by visiting DC - Tax Forms )
