“He [Garcia] denied for a long time that the problem even existed,” said Lopez-Cantera, adding that recent stepped-up efforts by Garcia’s office come on the eve of the election. Lopez-Cantera questions whether the recent contract the property appraiser signed for high-tech data-mining capability is the best approach.

Garcia insists that he has been targeting homestead fraud since taking office as Miami-Dade’s first elected property appraiser in 2009, boosting county liens for undeserved homestead claims to $8 million in 2011 from $3.6 million in 2008.

“If my mother were alive and she were claiming homestead illegally, she’d be in trouble,” Garcia told The Miami Herald.

The difference in tax on a property with homestead and one without can be enormous. Homestead status excludes $50,000 from the assessed value (but only $25,000 for school taxes) used to calculate property taxes. But that exemption is peanuts compared to the savings many get from the Save Our Homes cap.

Under the Save Our Homes constitutional amendment, which took effect in 1995, the taxable value of homestead property can rise no more than 3 percent a year — no matter how much market value goes up.

Over time, the cap on assessments has spawned drastic tax differences on similar residences, with some people paying double or triple the taxes as a neighbor in a similar home, based on the value at the time homestead status was locked in.

Even with the historic collapse in home values, $13.4 billion in Miami-Dade residential value is excluded from taxation this year because of Save Our Homes. That is down from $66 billion in property value that was kept off the tax rolls by the cap in 2008 before the bubble burst.

With homestead status dating to 1996, the bayfront property on Northeast 84th Street owned by Joseph and Sheron Barnes had a taxable value of $489,554 in 2008 — less than a fifth of its market value of $2,682,813.

After investigating anonymous calls, the property appraiser’s office filed a lien on the property, seeking back taxes, penalties and interest totaling $403.329.70 — the largest lien so far this year.

The property appraiser claims the home was rented in 2005. That would nullify its homestead status, unless the owners had moved back in and reapplied, said deputy property appraiser Lazaro Solis.

Other reasons for the big tab: Property appraiser records say the home, which is in foreclosure, was abandoned. The Barneses couldn’t be reached for comment.

After a lien is filed, the county doesn’t sell tax certificates or seek foreclosure. But the tax bill must be paid before a property can be refinanced. When a property with a tax lien is sold, the county and other taxing authorities like the school district are the first in line to collect — ahead of any mortgage holder.

Some people pay the bill right away. That was the case with Escagedo, who owns the home at 13180 Old Cutler Road. She recently paid $156,676.85 for back taxes, penalties and interest for 2001 through 2010 after the property appraiser sent her a notice of back taxes due because she also had a homestead exemption for 13720 Farmer Rd.

Reached by telephone, Escagedo said she paid the tax bill promptly and didn’t want to air the details. “There was no lien filed,’’ she said.