The 50 largest companies in the United States have more than $1.3 trillion US stashed in offshore tax havens, anti-poverty charity Oxfam says.

The British group said Thursday that the widespread practice of stashing profits in offshore jurisdictions with favourable tax regimes, instead of repatriating them where they can be invested and taxed, costs the U.S. government roughly $111 billion a year.

That money is held in a byzantine network of at least 1,608 subsidiaries, Oxfam calculated, all solely designed to hold profits that would otherwise be subject to higher taxation, but would also be available to be invested into their businesses.

The practice, Oxfam says, doesn't just deny the U.S. government of those funds, but also siphons roughly $100 billion a year from poorer countries.

"The harm done to Americans and people living in poor countries by corporate tax dodging are two sides of the same coin," the group said in its report "Broken At The Top," released Wednesday.

Offshore Accounts Users Guide

The 50 largest companies in the U.S. have more than $1.3 trillion US stashed in offshore tax havens, Oxfam says. (Arnulfo Franco/Associated Press)

Technology giant Apple leads with roughly $181 billion stashed away. But other big names are not far behind.

According to Oxfam's analysis of the companies regulatory filings and other publicly available documents:

  • Apple has $181 billion stranded in foreign subsidiaries.
  • General Electric has $119 billion.
  • Microsoft has $108 billion.
  • Drug company Pfizer has $74 billion.
  • IBM has $61 billion.
  • Merck has $60 billion.
  • Consumer products giant Johnson & Johnson has $53 billion.
  • Google-owner Alphabet has $47 billion.

The sum of the 50 largest companies adds up to more than $1.3 trillion. For comparison purposes, that's almost as much as Canada's entire GDP, which the World Bank says clocked in at just over $1.7 trillion US in 2014.

Oxfam calculated those companies paid $1.051 trillion worth of taxes across all levels, to the U.S. government between 2008 and 2014, which was the timeframe Oxfam examined in the report.

"Profits disappear from countries where real economic activity is taking place to exist only in tax havens," Oxfam said. 

In 2012, for example, U.S. companies reported $80 billion of profits in Bermuda — a figure greater than their reported profits in Japan, China, Germany and France combined.

That same year, according to the Internal Revenue Service (IRS), almost 60 per cent of all the foreign earnings reported by U.S. multinational companies were on the books in just 10 notorious tax havens.

"We should not lose sight of why tax dodging matters to average people," Oxfam said. "This loss of revenue prevents adequate investment in education, infrastructure and other critical public needs that can reduce poverty, create jobs and build greater economic opportunity."