Beyoncé Dad Tax Bill -- Mathew Knowles Slapped With $1.2 Million Tax Bill, Bill, Bill

The Good News: Beyonce's dad, Mathew Knowles, raked in BOATLOADS of cash during the years he managed B's career ... we're talkin' millions.

The Bad News: The IRS says he still owes all sorts of taxes on some of that income -- over $1.2 MILLION.

Uncle Sam just filed a ridiculously large lien against Knowles, claiming he needs to cough up some cash from the years 2010 ($485,575.95) and 2011 ($728,004.89) ... all totaled, $1,213,580.84.

It's no wonder the bill is so high ... Beyonce is arguably one of the highest grossing musical talents OF ALL TIME -- and during the years 2010 and part of 2011 MK was still managing her career. Not to mention his slew of other projects, including his own record label.

Seriously, when your tax bill is over a million ... you're pretty rich.