The amount of unpaid real estate and personal property taxes in Loudoun County has more than doubled this year, driving collection rates down to the lowest levels since 1982, the year of the last recession.

Most of the increase comes from unpaid bills owed by developers, Loudoun County Treasurer George Titus said. The amount of unpaid taxes jumped from $1.2 million last year to $2.6 million.

Titus said the shortfall highlights the financial troubles of much of the development community in Loudoun, which has been plagued by rampant overbuilding and a sharp fall in land prices that once were pushed upward by real estate speculation.

Other Washington area counties have experienced a similar rise in the number of delinquencies, tax officials say. The amount of taxes paid as of Sept. 30 dropped about 3 percent in Prince George's County, and about 1 percent in Anne Arundel County, even though late payments continue to arrive. Officials in both counties point to a softening of the economy.

In Fairfax, Montgomery and Arlington counties, where many of the region's white-collar workers live, tax officials say payments haven't slacked off. But Arlington Treasurer Francis O'Leary said those areas may be hit next by delinquencies, particularly if the federal government cuts back on spending.

"We're not looking forward to the next year . . . . It's much nicer to be a tax collector in benign times," O'Leary said.

Loudoun officials said they will get nearly all the money through court judgments, tax liens and other collection methods. But the delinquencies force the county to borrow money in the short run, which costs taxpayers more in interest, he said.

"They're just tough times," said Titus, who noted a surge in trustee sales of property in Loudoun in recent months. "They {developers} are trying to figure out where they are going to get the money."

According to Loudoun County financial statements, the tax collection level was 97.32 percent when the fiscal year ended in June, a drop from 98.45 percent in fiscal year 1989 and 98.64 percent in fiscal 1988.

The delinquent taxpayer with the largest bill in Loudoun County is the Alan I. Kay Co., a development firm in Bethesda that owes nearly $500,000 in taxes, penalties and interest on four parcels of land in the eastern part of the county.

A developer of office buildings and warehouses, Alan Kay said Loudoun was hit by the tight credit and saturation of office space that also have stymied the economy in other areas. But he said the downturn shows up more clearly because investors had more land to buy and a better chance to overextend themselves.

His company bought the land near Route 7 and Route 28 at high prices in the last few years and hasn't been able to develop it, he said.

Huntmar Associates Ltd., of Vienna, owes $125,919 on a warehouse and office development near Route 606, said Stuart Gary, a Huntmar vice president. He attributes Loudoun's trouble, in part, to speculation, which pushed up the price of land and office space, and bad press, which he said undercut investor confidence.

"Real estate is probably as close to a depression as this area has seen," Gary said.

Fred Hetzel, a real estate agent in the county for about 20 years, disagreed, saying Loudoun still has enormous potential. But he admitted there is little market for undeveloped land. He blames inflated tax assessments in recent years for some of the tax troubles people face.

"I've got property that is assessed for literally twice what it could sell for right now," said Hetzel, owner of Coldwell Banker/Fred Hetzel and Associates in Leesburg.