Bale is waiting in Madrid for the green light to fly to London to sign the contract.
If the deal go through it will see Bale return to the club he left in a world-record £86m transfer seven years ago.
Lawyers in Spain and England are working on drawing up contracts which will make Bale a Spurs player again. Spurs have agreed to pay about £20 million in wages and loan fees.
Although he played for Wales twice this month, he is not fully match fit and it is expected it will take a month for him to get back to his best.
A source close to the negotiations says progress is slow at the moment but there is an expectation on all sides that a deal will be completed. When asked if Bale would become a Spurs player soon, the source said: “Of course.”
Madrid have agreed to let him leave on loan in order to get his £500,000-a-week wages off their books and Tottenham have made all the running to sign him this week.
As well as being frozen out by Zinedine Zidane, Bale has had a difficult relationship with the Spanish media and Madrid fans, and he is looking forward to making a fresh start back at Spurs.
Manchester United considered making a move for him as a back-up option to Jadon Sancho, but they did not make an offer, even though they have tried to sign him on numerous occasions since he was at Southampton 13 years ago.
