HONOLULU -- Oahu homeowners swamped the city's real property tax office with phone calls and e-mails on Monday.

Many are responding to property value notices that they received Friday and Saturday in the mail. The notices showed an average 25 percent increase in property values across the island, and so people are facing much higher property tax bills.

More than 100 people e-mailed the city about their assessments Monday. At least 25 people called by telephone every hour. Property owners are calling to get tax officials to explain their rising property values.

Some people went in for an explanation, like Mario Fiore, 74, who is a barber at a Waikiki hotel. He wants to know why his property tax bill will be so much higher.

Fiore sat down with an appraiser, who explained recent real estate sales near the two-bedroom apartment Fiore and his wife own in Kaimuki. He wanted to know why his assessment went from $169,000 with a $184 bill this year -- to $297,000 next year and a tax bill of $663 if the City Council leaves tax rates were they are.

"That's outrageous," Fiore said.

He is filing an appeal.

"I don't think that's fair to pay that amount of money from old people," Fiore said.

City Real Property Assessment Administrator Gary Kurokawa said while many homeowners aren't happy there are clear reasons why the numbers are up.

"I think the general public understands that the market has been moving upwards within the last two years, so they're not taken totally by surprise," he said.

Kurokawa suggests homeowners check to make sure they're getting all the exemptions they're owed based on age, income, veteran's status or disability.

If you think the city's assessment of your property is exceedingly high, he recommends calling.

"They need to call our office. We can have someone explain how the valuation was done and answer any other questions they have about their property values," Kurokawa said.

In order to successfully appeal your assessment, you have to prove to an appeal board, using comparable sales information, that your property has not been valued accurately. Property owners can't simply complain that they don't want to pay higher taxes. They need to take that complaint to the City Council and the mayor if they think the politicians should lower the property tax rate to lessen those tax bills.