Something spooky happened to new homeowner Antolin Ortiz a few weeks shy of Halloween, when he opened his first-ever property tax bill.

He’d picked up a bargain-basement Salinas fixer-upper for just $75,000 in July, but the Assessor’s office valued it at $200,000, and billed Ortiz some $2,000, or more than double what he actually owes.

The reason for the discrepancy? Chalk it up to a still-plummeting housing market.

This year’s taxes are based on assessments as of Jan. 1, when Ortiz’s home was worth $200,000. Just seven months later, it had lost more than half its value.

“It was a little strange,” a relieved Ortiz said after a conversation with a clerk at the Assessor’s Office. He’ll have to pay the bill, but he can expect a reimbursement check from the county later.

“We never had this problem before,” County Assessor Steve Vagnini says. “We’re chasing the market down.”

This is the first year ever that the overall assessed value of all county properties has declined, Vagnini says. “It was the same in the whole state of California.”

As tax bills arrived in mailboxes last week, a full third of county taxpayers got relief in the form of a reduction, which marked another first in Vagnini’s 24-year career at the Assessor’s office. The rest got 2 percent increases based on the cost of living, even though many homes are worth less than they were a year ago. Such increases are allowable as long as a property’s assessment doesn’t exceed its market value. Because of Proposition 13, longtime homeowners are still paying taxes based on very low 1970’s-era assessments, Vagnini says.

The Assesssor’s office had braced for a flood of calls, visits and appeals from angry taxpayers whose home values have tanked, but instead it’s been more like a steady stream. With more than a month left before the Nov. 30 deadline, nearly 400 people have already filed appeals—more than the total number who did so in 2007, before the housing market took a dive. Still, Vagnini predicts that most of those will be settled informally once taxpayers understand the 2 percent hikes are legal.