Automated determination of a timing offset for DOCSIS time protocol to provide precision time protocol accuracy. A cable modem receives, from a cable modem termination system (CMTS), a message that includes a timestamp that is correlated to a primary reference clock. The cable modem determines a downstream travel time representative of a period of time between a generation of the timestamp by the CMTS and a first timing reference point of the cable modem. The cable modem accesses an internal delay time representative of a period of time for the timestamp to travel from the first timing reference point to a second timing reference point of the cable modem, and sets a precision time protocol (PTP) clock of the cable modem to a time equal to the timestamp incremented by the downstream travel time and the internal delay time.