Boston?s mayor is continuing his push for the closure of a nearly 100-year-old tax loophole that reduces real estate assessments for telecom companies if their Massachusetts assets are owned by an out-of-state corporation.

While MCI, AT&T and Sprint are among those accused of avoiding responsibility as corporate citizens, Verizon Wireless ? which registered its Massachusetts subsidiary as a corporation based in Bermuda ? is being regarded as the biggest offender.

For the 2003-2004 tax year, the Boston Globe reported that Verizon Wireless succeeded in lowering its assessable real property by 99.7 percent. It paid more than $3 million a year to the city of Boston when its legal ownership of assets was based in Massachusetts. Now, that it has moved the assets to a Bermuda-based corporation the company?s annual tax bill is $9,307.

Boston Mayor Thomas Menino and the Communication Workers of America (CWA) union are among those pushing for the loophole to be closed.

Mayor Menino wrote in a column last Monday that any revenue collected from the passage of the bill would be used for property tax relief and would mean the lowering of the business tax rate by two percent and savings for the average single family homeowner of $185 each year.

Industry lobbyists argue that higher telecom property assessments would result in companies having to pass on their costs to customers.

?This is a tax that cannot be absorbed by the industry,? Joseph Zukowski, a Verizon vice president, told the Legislature?s Revenue Committee at a hearing last month before the State House before the Joint Committee on Revenue.

In testimony in support of House Bill 2408 ? An Act Relative to the Taxation of Telecommunication Companies, Mayor Menino, who said that he filed the bill ?to level the playing field among business, and help ease the commercial and residential property tax burden?, said phone companies are making ?the same tired arguments that simply don?t hold any water.?

Mayor Menino said telecom companies have saved $31 million on local property taxes this year through aggressive use of tax provisions including transferring title to telecom assets to new Bermuda- and Delaware-based companies.

?Did customers see their bills go down? No,? Menino said.

The CWA?s Steve Early told the committee noting that Verizon?s total revenues were $27.7 billion last year and its net profit increased from $3.1 billion in 2003 to $4.7 billion in 2004.

?Verizon Wireless has 197 subsidiaries in the United States,? Mr. Early said. ?Only one is incorporated outside the country ? Bell Atlantic Mobile of Massachusetts Corp., Ltd., which is based in sunny, tax-dodging Bermuda.?

The co-chairs of the Revenue Committee have not set a date for a floor vote on the proposal.