Washington DC taxis now charge by mileage rather than by zones:
Initial 1/6 mile or fraction thereof: $3.00
Each additional 1/6 mile or fraction thereof: $0.25

Each additional passenger, after the first (children under 6 ride free ): $1.50
Surcharge for each trip originating at the Reagan National Airport taxi stand: $1.75
Luggage:
-Each bag in excess of one handled by the driver: $0.50
-Each trunk (any article in excess of 3 cubic feet or 32 x 18 x 9 inches ): $2.00
Request by phone:
-Dispatch fee $2.00
-Dismissal without use (after cab has arrived ): $1.50
Small animal not enclosed in box or basket (except guide dogs ): $1.00
Personal service when requested by the passenger: $2.00