The central defender left Spurs to join Cardiff in a deal worth £9 million at the start of the season, much to the surprise of the north London club's fans.
The 22-year-old had come up through the ranks at Tottenham but was allowed to leave with the arrival of Vlad Chiriches on the horizon.
Now according to the Guardian, Spurs are looking at the possibility of taking him back to White Hart Lane, and could swoop if Cardiff are relegated.
They claim there are doubts over the future of Jan Vertonghen, who has previously hinted that he could leave if Tottenham don't get a top four finish which looks highly unlikely. He's been linked with a move to Barcelona.
Younes Kaboul is also out of contract in the summer and could leave given his injury problems over the past few seasons.
Although it is unclear whether Caulker would be open to a return to Spurs, he is likely to be keen on working with Tim Sherwood again having been guided by the former Spurs midfielder during his time in the club's youth system.
However, given the doubts over Sherwood's future as manager of the club, there are no guarantees that the pair will be reunited.
Tottenham currently sit in 6th place in the Premier League, and go head to head with Liverpool at Anfield on Sunday.