Katt Williams -- I Make $28,000 a MONTH!!!

In between custody battles, tractor stand offs, and being arrested ... comedian Katt Williams somehow rakes in $28,000 a MONTH -- this according to new legal docs.

You may recall ... Katt won back custody of his 8-year-old adopted daughter from his former nanny in December -- after a protracted legal battle -- and just filed new documents in the case, updating L.A. County Superior Court on his financial status.

In the docs, Katt lists his average monthly income as $27,778 -- money he claims to make as a freelance comedian.

Katt’s got some serious disposable income too -- according to the docs, his monthly expenses are only $7,000 ... leaving him roughly $20K a month to blow on whatever he wants, like bail.