Rory McIlroy could face losing nearly half of his £3.2 million prize money if he wins the Masters Tournament on Sunday.
McIlroy enters the final round with a two-shot lead over nearest rival Bryson DeChambeau at the top of the leaderboard.
The Northern Irishman, who hasn't won a major since 2014, is 12-under-par after carding two consecutive rounds of 66 on days two and three.
McIlroy hit two eagles in his third round - something he has never previously done in a Masters round in his career.
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The battle between himself and DeChambeau now promises to be one for the ages at Augusta National, particularly as the American came from a shot back with three holes to play to defeat McIlroy at last year's US Open.
And McIlroy is also aiming to become just the sixth player in history - after Tiger Woods, Jack Nicklaus, Gary Player, Ben Hogan and Gene Sarazen - to complete a career grand slam by winning all four PGA Tour majors.
The total purse on offer for the 2025 Masters is $21 million, with $4.2 million (£3.2 million) - alongside the iconic green jacket - awarded to the winner.
Should McIlroy succeed on the greens of Augusta National, Georgia on Sunday, he faces giving up not far from half of the prize money instantly.
That is because, according to a tax expert, he would face a tax bill totalling 42.39 per cent (around $1.2 million) to be deducted from his winnings.
Paul Barham, head of international private client tax at Forvis Mazars, told the Daily Express: "Any prize money earned will be subject to US federal tax, the top rate of which is still 37 per cent.
"Golfers will also have to pay state tax in Georgia at 5.39 per cent.
"The US tax will be paid by all golfers playing at Augusta regardless of where they are tax resident and if they are a tax resident in the US, they shouldn't pay tax on this prize money in any other country."
McIlroy is a US resident, as he lives in Florida with his wife Erica Stoll, as well as his daughter Poppy, who was with the Northern Irishman at the traditional Par 3 Tournament at Augusta on Wednesday.
The four-year-old provided fans with one of the most heartwarming moments of the Masters when she sunk an incredible putt on the ninth green, sparking wild celebrations from McIlroy and his close friend Shane Lowry.
Speaking after his third round, the 35-year-old revealed how his wife and daughter were helping him prepare for the Masters.
"I watched a little bit of Premier League football this morning, and then I actually watched Zootopia with Poppy. Very, very good movie if anyone's interested.
"I'll have some dinner tonight. Maybe try to make it through the second episode of the third season of Bridgerton. Fell asleep during episode one last night.
"And that's it. Yeah, sort of put the phone away. Don't look at it. Try not to look at it until tomorrow night."
Topics: Rory Mcilroy, Golf
Ryan Smart