R. Kelly -- I Believe I Can ... Not Pay My Taxes

The federal government is pissed at R. Kelly ... for failing to pay a whopping $4.8 million in back taxes ... TMZ has learned.

According to documents filed by the IRS, Kelly owes money on his taxes going way back to 2005. It breaks down like this ...

2005 - $1,472,366.77
2006 - $710,520.51
2007 - $376,180.11
2008 - $1,122,694.90
2009 - $173,815.18
2010 - $992,495.24

... for a total of $4,848,072.71.

Being trapped in the closet probably won't cut it as an excuse.

A rep for Kelly tells TMZ, "R. Kelly is in the process of working everything out with the government and is confident that all his obligations will be satisfied."