Ten multinational U.S.-based corporations, including Apple, Merck, Microsoft and Pfizer, each increased their foreign profits by $5 billion or more last year, continuing a trend in which U.S. corporations held more of their money in low-tax countries.

A new report by the advocacy group Citizens for Tax Justice found that 92 Fortune 500 corporations boosted their offshore holdings by over $500 million each. Ten companies reported that their offshore profit holdings have grown by more than $5 billion each in the past year. Apple reported adding $28 billion in offshore cash in the past year, while Microsoft’s offshore stash increased by $16 billion.1 Other Fortune 500 companies that added at least $5 billion offshore in the past year included Pfizer, Merck, Google, Abbott Laboratories, Johnson & Johnson, Citigroup, IBM and General Electric. The 10 companies collectively increased their offshore profit holdings by a total of $107 billion in just the past year.

In the same year, 92 Fortune 500 corporations each boosted their reported offshore profit holdings by at least $500 million. In total, these 92 corporations added an additional $229 billion to their offshore profit hoards in 2012 alone.

Under current corporate tax laws, foreign profits are not subject to U.S. tax until the profits are repatriated to the U.S. According to Congress’s Joint Committee on Taxation, this indefinite deferral of tax on profits ostensibly earned or shifted overseas will cost the federal government about $600 billion over the course of the next decade. A December 2012 CTJ report found that nearly 300 Fortune 500 corporations have disclosed holding at least some profits overseas, collectively holding over $1.6 trillion offshore at the end of 2011.

Of this group, 47 corporations indirectly disclosed how much in taxes they would owe the IRS if their $384 billion in offshore profit holdings were subject to the U.S. corporate income tax. For these companies alone, taxes due would total $105 billion, indicating that most of those profits have been shifted out of the U.S. into foreign tax havens where the companies do no actual business.

“Lobbyists for the multinationals are urging Congress to go even further, by permanently exempting from U.S. corporate income taxes all profits that U.S. corporations manage to have treated as ‘foreign,’” said the report. “Such a change would make it even more profitable for multinational corporations to shift jobs and profits out of the United States, and could cost the U.S. government hundreds of billions of dollars in additional lost revenues.”

Sen Carl Levin, D-Mich., and other Senate Democrats have introduced a series of bills in recent years aimed at curbing the use of offshore profit shifting by multinational corporations (see Senate Democrats Introduce Legislation to Eliminate Corporate Tax 'Loopholes'). However, Levin announced plans last week to retire in 2014.

Over the past four years, 48 corporations each added at least $3 billion to their offshore profit holdings. The total that these 48 companies added over four years was $518 billion. Apple topped the list, adding $65 billion to its offshore holdings of cash and marketable securities over the past four years.