TAMPA - Hillsborough County homeowners with toxic drywall imported from China could get a big break on their property taxes. But county government revenues will have to pay the price, up to $5 million by some estimates.

The Hillsborough County Property Appraiser's Office is evaluating homes and offering a discount of up to 50 percent of the value, depending on the severity of the drywall problem. The value of the land would not be included in the deduction.

"We don't want to make it even more difficult for people already burdened by this problem," said Warren Weathers of the property appraiser's office. "We wanted to respond to this quickly."

Homeowners can call the office at (813) 272-6100 to inquire about the deduction.

Homeowners have complained their drywall emits a corrosive gas that damages appliances, gives off a rotten-egg stench and may cause health problems.

Many of the homeowners struggling with bad drywall can't live in their houses, Weathers said, and even if they could sell them, the value would be diminished by the drywall.

It is unclear how many homes could be eligible for the deduction. Weathers estimates as many as 2,500 homes in the county could have the bad drywall but said that's a "worse-case scenario."

The drywall was used in as many as 100,000 homes across the nation during the housing boom, and most so far have been found in Florida.

The effect of the drywall is still under investigation, but health complaints include dry eyes and respiratory problems.

Builders typically use domestic drywall but a drywall shortage during the housing boom led them to use imported drywall from China. Most of the affected homes were built from 2004 through 2007.

Warren said 159 homeowners have registered for the tax break so far, and many homeowners may be unaware of the opportunity.

Once a homeowner registers, a county property appraiser will inspect the home and seek documentation that proves the problem, such as a letter from the builder.

Some builders are replacing the drywall and appliances. Builders have said it costs roughly $100,000 per home to do the work. It requires homeowners to move out for months while the work is done. Many homeowners don't have this opportunity, though, because their builder has gone out of business.

Meanwhile, other homeowners are seeking legal action. Class action lawsuits against builders and manufactures are pending.

The Hillsborough property appraiser's effort follows an announcement in July that the Internal Revenue Service may give homeowners with drywall problems some relief on their tax returns.

The IRS is considering whether to allow homeowners to claim a casualty loss on their tax returns if they have Chinese drywall emitting an "unusual or severe concentration of chemical fumes that causes extreme and unusual damage."

It is unclear exactly how much homeowners could claim, but the IRS said similar tax breaks use the difference between the value of the house before and after the event causing the damage.

Reporter Shannon Behnken can be reached at (813) 259-7804.