Floyd Mayweather, shown in 2014, has had several liens filed against him by the IRS. (John Locher/Associated Press)

We thought we already knew why Floyd Mayweather was coming out of retirement to fight Conor McGregor. He had stated that he would not do so for less than $100 million, and the UFC superstar provided the grabby name for just such a payday, while McGregor’s complete inexperience in a boxing-only matchup would likely help Mayweather boost his record to 50-0.

But a new reason emerged Monday: Mayweather needs some help in paying his 2015 tax bill.

That’s according to Forbes, which reported that the boxer filed a petition with U.S. Tax Court to forestall any action on those IRS-related liabilities until after the McGregor fight, scheduled for Aug. 26. The event is expected to generate hundreds of millions in total revenue, with Mayweather earning a nine-figure sum, much as he did for fighting Manny Pacquiao in May 2015.

“Although [Mayweather] has substantial assets, those assets are restricted and primarily illiquid,” the petition, filed last week, states. “The taxpayer has a significant liquidity event scheduled in about 60 days from which he intends to pay the balance of the 2015 tax liability due and outstanding.”

Mayweather is also asking for the IRS to waive certain failure-to-pay penalties, but the IRS’s position is that he has the ability to settle the bill by selling off a few of his assets. The agency has had several interactions with Mayweather in the past, reportedly filing liens against him at least five times since 2001.

Mayweather, who goes by the nickname “Money” and licenses a slogan, “The Money Team,” on merchandise, frequently flaunts his wealth on his social-media accounts. That often includes showing off huge amounts of cash, as well as expensive cars and massive wagers on sports events.

I bet on @isaiahthomas today! ☘️ #TMT

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This Halloween costume speaks for itself, "Money Man".

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They say "Life Is What You Make It" and to that, I'll agree wholeheartedly! As I sit here acknowledging how blessed I am to be retired a year shy of my 40th birthday, it's nearly impossible to say that I am not living the "American Dream". Without my usual six-pack or muscle tone in sight, I can sit back and get the last laugh, knowing that I put in the "Hard Work & Dedication" to be 49-0. I'm blessed to wake up every morning, certain that my bank accounts are growing. Making 7 figures monthly without moving a finger, just further proves that I've made brilliant investments and decisions that allow me to walk away from the ring, comfortably. I'm proud to be a King. Video credit: @greg_larosa_tmt www.themoneyteam.com

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Monday also brought word that the Mayweather-McGregor fight pay-per-view will cost $89.95, plus an extra $10 to watch it in high definition. That is the same amount as was charged for the Pacquiao fight, which left many viewers feeling very unhappy, given the desultory nature of that contest, won by Mayweather in a unanimous decision.

Fight fans can only hope that the McGregor bout offers more excitement, even if the Irishman comes in as a major underdog. The star power involved makes the event impossible to ignore, but it’s not exactly a major selling point that Mayweather may only be returning to the ring to get the IRS off his back without sacrificing any of his fleet of luxury vehicles.