The 44-year-old American has registered with tennis' disciplinary unit ITIA to be available for doping tests.
Serena Williams will not be able to compete again until six months at the earliest.
According to The Guardian, rumors suggest a possible comeback could take place at next year's US Open, and in the mixed doubles or doubles with sister Venus, 45. The older sister returned to tennis this summer after a 16-month hiatus.
The last time Serena Williams played an official match was in the third round of the 2022 US Open.
