"I would say that from the review of the records, it appears that the half-bath wasn't correctly entered into the old database and wasn't converted into the new database and it was not included in his assessment," Jankowski said in an interview.
In all likelihood, Jankowski said, Mangano's central air-conditioning wasn't included either, since assessments are based on inventory information from the department's Integrated Assessment System, or IAS, database - which listed Mangano as having central heat, but not central air-conditioning.
A county spokesman said last month that Mangano's most recent assessment was correct because the improvements, which could add as much as $25,000 in value, had been included. But Jankowski said in the interview that Mangano's assessment was, indeed, incorrect. Those improvements could have added more than $450 to Mangano's property tax bill of $14,272 this year.
Mangano, in an interview late last week, said that he continues to think he is overtaxed. He noted that if he had grieved his assessment previously, it likely would have gone down.
"It is an error-ridden system" that needs reform, he said.
Last month, Newsday reported that Nassau's public assessment Web sites provide inaccurate information about Mangano's Bethpage home, omitting the half-bath and central air that town records show are part of his 3,690-square-foot house.
Officials say the errors are not Mangano's fault but are likely inputting mistakes or stem from the conversion to new software systems.
A New York certified general appraiser, Ken Rossman, said nearly any appraiser would make an upward adjustment in value for an additional half-bath and central air-conditioning in a house as large as Mangano's.
"Most [mortgage] underwriters would object if we didn't make an adjustment for it," Rossman said.
The flawed description of Mangano's house had not been corrected at week's end on the county's public Web sites, although Jankowski said it has been fixed in the department's internal database.
with Randi F. Marshall