Lindsay Lohan -- IRS Cracking Down Over MASSIVE Tax Debt

Lindsay Lohan has a brand new $93,000 problem -- because the federal government claims the actress never paid her 2009 income tax ... and now Uncle Sam is finally out to collect.

According to official documents filed in Los Angeles, the Internal Revenue Service has obtained a lien against Lohan for $93,701.57 for failure to pay her federal income tax.

2009 wasn't a very lucrative year for Lohan ... she only released one crappy made-for-TV movie, coupled with a few minor TV appearances.

Now, if Lohan refuses to pay the debt ... the government can go after anything that belongs to her ... including homes, cars and bank accounts ... assuming she has any of those things.