According to a report by The Athletic, the transfer fee agreed between the two clubs is close to 35 million pounds (Rp. 792 billion).
"This transfer would be the fourth most expensive sale in Tottenham's history, behind Gareth Bale, Harry Kane and Kyle Walker, although Johnson is not part of head coach Thomas Frank's long-term plans," The Athletic wrote on Tuesday.
If the 24-year-old Wales international agrees to the move, he would bolster Palace manager Oliver Glasner's attacking options for domestic and European competition.
The Eagles currently rely on Jean-Philippe Mateta, Eddie Nketiah, Yemery Pino, Ismaila Sarr and Daichi Kamada.
Johnson finished last season as Tottenham's top scorer with 18 goals in all competitions, but his role has been reduced since Thomas Frank took over as Spurs manager. He has started just six Premier League games.
