As things stand, the South Korea attacker could leave the club for nothing at the end of the season, having entered the last 12 months of his contract at the Tottenham Hotspur Stadium.
Should Son not pen a new deal between now and January, he will be able to enter talks with foreign clubs when the New Year rolls around, and he is thought to be a target for the Saudi Pro League.
Now 32 years of age, Son - who turns 33 next July - remains as pivotal as ever to Ange Postecoglou's system and has already registered two goals and two assists from five Premier League matches this season.
The former Bayer Leverkusen star set up two goals in the weekend's 3-1 victory over Brentford while creating seven chances in total, but he recently revealed that no talks had started over a new Spurs contract.
Tottenham 'will trigger' Son's one-year extension
However, the Evening Standard now reports that Spurs will activate the 12-month clause in his contract, thereby keeping Son at the Tottenham Hotspur Stadium until at least the summer of 2026.
Whether the 32-year-old's short-term extension will precede a long-term renewal is not known, but if nothing else, Spurs will be protecting his value by keeping him on the books for another year.
Should Son fulfil the terms of his contract after Spurs activate the clause, he would have spent 11 seasons in North London, having joined from Bayer Leverkusen in a €30m (£25.1m) deal in 2015.
The South Korea international has contributed 164 goals and 86 assists in 414 matches for the Lilywhites in that time, and only four players - Harry Kane, Jimmy Greaves, Bobby Smith and Martin Chivers - have scored more for Tottenham.
Son is therefore the highest non-English male scorer in Spurs' history, but the 32-year-old has never won a piece of silverware with the North London giants, whose last major trophy was the 2007-08 EFL Cup.
Is extending Son's contract the right decision?
There is no escaping the fact that Son is approaching the twilight of his career, but the South Korea captain is evidently still in fantastic shape and has picked up where he left off after a stellar 2023-24 campaign as Tottenham captain.
Son may have lost his deadly double act partner in Kane last year, but he brings unparalleled leadership and versatility to an otherwise youthful Tottenham XI, as well as an impeccable fitness record.
Over his nine years in North London, Son has only missed 44 matches for both club and country through injury or illness, and the longest he has ever been out for is just over two months, when he broke his arm in 2020.
From both a playing and financial point of view, tying Son down for another 12 months makes perfect sense, although it would be interesting to see if Daniel Levy sanctions a two, three or even four-year extension for the forward in 2025.
If not, then Spurs could still recoup a decent amount of money for one of their most loyal servants next year, if he does decide that one last mammoth payday in Saudi Arabia or the USA - or even a return to his homeland - appeals to him.