Rapper Nelly either hasn't been checking his mail as of late or he's been living irresponsibly, as the 37-year-old Missouri native owes major money to his credit card company.

TMZ reports that the Grammy-winning entertainer totaled $20,403.64 for an American Express credit card bill. American Express claims the rhymer hasn't paid up on the monies owed to the company, even after being sent a notice about the amount.

The credit card company filed a lawsuit against Nelly in October, according to the tabloid website. The suit demanded that the 'Country Grammar' star, born Cornell Haynes, Jr., pay back the more than $20,000 and an additional $3,000 in lawyer's fees, which have yet to be paid.

A court hearing Nelly must attend is set for Jan. 9, 2012.

Watch '10 Biggest Selling Hip-Hop Acts In US History'