Christie Brinkley -- Sorry I Blew Off The IRS & My Taxes

Christie Brinkley vows to repay the IRS the $500k she owes in back taxes by Wednesday -- telling TMZ, "I regret not paying more attention to my accounting."

Brinkley -- who's worth a frickin' fortune thanks to modeling, infomercials, endorsements and real estate -- was hit with a tax bill to the tune of $531,720 back in November.

Now, the supermodel tells us, "I was surprised to learn of the tax lien filing and took immediate steps to rectify this matter. I discovered the tax lien was the result of an error."

Brinkley adds, "My taxes will be paid in full by Wednesday, December 7th and I expect the tax lien to be released immediately thereafter."

"I regret not paying more attention to my accounting, but I have been, and remain focused on my whole family as both my parents navigate serious health issues."