"The revenues from residential transactions have been dropping pretty steadily since about last December - almost a year now," he said.

Some taxpayers may have deducted home improvement costs to adjust their profits on a series of residential transactions as they traded up.

"I'd rather not go into my residential transactions, at this time."

The company provides title and escrow services, post-closing services, and insurance services for commercial and residential transactions.

The residential transaction can be stressful for all the parties: buyers, sellers, brokers, even the lenders.

"My guess is that in many cases they don't tell the purchaser because the savings may be marginal in a residential transaction," he said.

Second-home sales now account for almost 6 percent of total residential transactions, according to the National Association of Realtors.

Mr. Florance, who has been developing CoStar since the mid-1980's, said commercial real estate lends itself to rigorous financial analysis more than residential transactions do.

The majority of residential transactions are very simple: 99 percent can be done without a broker.

Over all, there were 8,879 closed residential transactions in Westchester in 2001 - 6 percent fewer than the previous year, the Listing Service reported.