DC has reciprocity with every single state. As such, only residents of DC file tax returns with DC. Nonresidents of DC only file the Form D-40B- Nonresident Request for Refund -if taxes were withheld for DC, as this is an error.
If you didn't live in DC, and didn't have DC taxes taken out by mistake, then you don't have anything to mail to DC.
Did you have DC taxes withheld? (I'm assuming not)
