Floyd Mayweather is adamant he's not in a huge hole when it comes to income taxes -- claiming he paid the IRS $26 million in 2015 ... saying, "What else could they possibly want?!"
TBE is firing back at reports he can't pay off his tax liability from that year and has asked Uncle Sam to cut him a break until after he gets his check from the McGregor fight.
FYI, 2015 is the year he fought Manny Pacquiao -- for which he reportedly hauled in roughly $220 million.