Jermaine Jackson claims he can't afford to pay child support because his business is failing and his career is in the tank -- in fact, according to new legal docs, MJ's bro can barely make ends meet.
Jermaine just filed new child support papers in L.A. County Superior Court -- obtained by TMZ -- grousing that he's expected to pay $3,000 a month in child support for sons Jaafar and Jermajesty ... even though his average monthly income for the last year has been under $1,100.
Jermaine is asking the judge to slash support payment to $215 a month.
According to the docs, Jermaine made a onetime appearance on "Big Brother" back in 2007, raking in a handsome $450,000 for his troubles -- but since then, Jermaine claims his business has floundered.
Jermaine claims his baby mama Alejandra not only earns more than him ... but she gets a free ride along with his kids at the Jackson compound, thanks to Katherine's generosity. Katherine has asked Alejandra to move her family into a nearby Jackson condo but Alejandra has refused and Katherine won't put her foot down.