Lindsay Lohan -- Six-Figure Payday Before Rehab

Lindsay Lohan has scored herself a HUGE paycheck before she goes into rehab, and TMZ has learned she'll be earning her keep by hanging out in South America.

Sources close to LiLo tell TMZ ... she's headed to Brazil this coming week to make a few appearances to promote a clothing line. We're told Lindsay scored a low six-figure payday for the deal.

Our sources say Lindsay will head down to Brazil on Wednesday (with a small entourage in tow) after she shoots her appearance on Charlie Sheen's show, "Anger Management." We're told Lindsay is scheduled to shoot her scenes Monday and possibly Tuesday.