Converting Single Family Home to Two-Family (DC)

[Anonymous]

I'd like to convert the basement in our single family home to a legal rental, so would need to get a two-family certificate of occupancy. Are there design-build companies that will deal with the permitting and licensing start to finish - in other words, file all necessary paperwork for the certificate and make sure all work is done to code? Also, any ideas as to time frame and total cost? There are separate front and rear entrances, the ceilings are high enough, and there is already a full bath in the basement, but the unit needs a kitchen installed and it needs to be reframed for living room and bedroom. Thanks!