It is understood that Chahar is currently at home as a close family member has not been keeping well and he urgently needed a break from the sport.
Chahar, in fact, missed the fifth and final T20I against Australia in Bengaluru, last Sunday, as he had to rush back home after being intimated about the family member's illness.
"Deepak hasn't yet joined the team in Durban as a close family member needed urgent hospitalisation. He had taken permission for a break as he needed to attend to his family member.
"He may or may not join the squad depending on his family member's health in coming days," a senior BCCI official told PTI on condition of anonymity.
The BCCI top brass understands that Chahar might not be in the best frame of mind till the family member fully recovers and hence if he doesn't wish to join the team now, he would be excused.
The 31-year-old Rajasthan veteran boasts best figures of 6/7 in a T20 International and his prolonged absence due to injury did affect the T20 squad's balance in the past two years.
With his incisive swing bowling in Powerplay overs, Chahar is an integral part of the T20I squad and the team management would like him to get as much game time as possible.
However, there remains a possibility that Chahar, who is also part of the ODI squad, will join the team during the second phase of the white ball-leg of the ongoing tour to SA.
However, the other two members of the T20I squad, Shubman Gill and vice-captain Ravindra Jadeja, who were holidaying abroad after the World Cup final have directly linked up with the squad in Durban and attended the practice sessions.