Even with debt, US not closing offshore loophole

“It’s the lobbying muscle,’’ Neal said. “Once something becomes embedded in the tax code, its very hard to extract.’’

Coincidentally, the aftermath of the tornadoes that tore through Western Massachusetts last month, causing an estimated $200 million in damage, offers a peek at the particular strategy on some insurance premiums that Neal and others say is unfair to US taxpayers.

Many of the storm damage claims in Westfield, Springfield, and Monson will be paid by overseas reinsurance firms, most with large operations in the United States and headquarters in Bermuda and Switzerland. The foreign reinsurance companies are not required to pay federal income taxes on the estimated $30 billion a year they shift from American subsidiaries to their offshore affiliates.

“It’s sophisticated tax avoidance,’’ said Neal, who serves on the House Ways and Means Committee, which has jurisdiction over tax matters. “Their presence is in the United States. Their post office box is offshore.’’

Tax specialists say it is just one example of the ways corporations legally move income from the United States to offshore accounts - and out of range of the IRS. The Congressional Research Service, a nonpartisan arm of the federal government, estimated last year that such shifting costs US taxpayers as much as $60 billion a year in lost revenue.

“It’s an example of a broader issue,’’ said Bret Wells, a professor and international tax law specialist at the University of Houston Law Center. Unless such practices are stopped, he said, more American companies will join the trend.

Offshore reinsurance companies say taking away the deductions on transfers would violate international trade agreements and lead to higher rates for homeowners and businesses.