Kelis isn't the only person trying to dig into Nas' pockets. Looks like the IRS has come a knocking, and they want their cut of his cash too.

TMZ has obtained a copy of a federal tax lien filed last month against the rapper for Nas for a whopping $2.5 million, for unpaid taxes and penalties from 2006 and 2007.

On top of this, the rapper has been ordered to pay his ex-wife Kelis $44,000 a month in child and spousal support, in the midst of a bitter divorce battle.

The decision came a day after Kelis delivered Nas' son, Knight, in July.