If you wish to pay a toll you missed on the Dulles Toll Road, please call the Customer Service Center at 877-762-7824. They are available Monday -- Friday from 7am -- 7pm. You will need the license plate number and state it was issued in for the vehicle you were in at the time of the missed toll, and they can look up and assist you with payment over the phone. They will charge an administrative fee to do this in addition to the cost of any missed tolls.
At this time, the Dulles Toll Road has no option to pay missed tolls on-line.