Christie Brinkley has been ordered to pay back more than $500,000 in unpaid taxes.

The 57-year-old model - who is believed to be worth around $80 million - claimed an "error" on her behalf was responsible for US authorities putting a lien on her $30 million mansion, and vowed to pay back The Missing $531,720 by tomorrow (07.12.11).

She said in a statement: "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.

"I am grateful for the outpouring of understanding and support I have received."

The Internal Revenue Service took out a legal claim on the former Sports Illustrated pin-up's 11-bedroom home, which is set in 20 acres of land in Bridgehampton, New York, due to financial irregularities that are believed to have been neglected by the star.

However, she maintains the lien came as a "surprise" to her.

Christie added in the statement: "I was surprised to learn of the tax lien filing and took immediate Steps to rectify this matter, which for most people is a private matter.

"I discovered the tax lien was the result of an error. My taxes will be paid in full by Wednesday, December 7 and I expect the tax lien to be released immediately thereafter."