When Congress passed the sweeping tax cut legislation late last year, one of its promised benefits was what would surely be a massive amount of repatriation of U.S. corporate profits held overseas for years to avoid the U.S. taxes on those gains. And in the three months ended in June, U.S. companies brought back roughly $170 billion in overseas profits, according to government report released this week.

That may sound like a lot, but it's far less than the $295 billion firms repatriated in the first quarter. The figure is about 17 percent of the the estimated $2.7 trillion held overseas, funds that have been stockpiled over years by huge companies such as Apple and Pfizer. Keeping profits earned overseas outside the U.S. helps companies cut their U.S. corporate tax bill, but they can't use those funds to invest at home.

The new tax law aimed to address that by using a lower, one-time 15.5 percent tax rate as an incentive to bring the funds back, with the idea that companies will invest in their U.S. operations, add jobs and boost the economy. President Donald Trump advocated for this portion of the law, predicting before the tax bill's passage that a mammoth $4 trillion would be repatriated.

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Earlier this week, The Wall Street Journal published an analysis of securities filings from 108 publicly traded companies that hold most of that $2.7 trillion, asking each company how it's using the money. About two-thirds of the $143 billion in public company repatriated funds the Journal identified came from two companies: Cisco Systems and drugmaker Gilead Sciences.

The paper noted that it's hard to tell how much of that cash can easily be brought back to the U.S., in part because companies do invest some profits earned overseas in offices, factories or people in the countries where they earned the profit. That means the funds are less liquid and harder to shift home, the Journal said, citing experts including Morgan Stanley analyst Todd Castagno.

Some companies that used to identify amounts held overseas in annual reports have stopped disclosing the information because the taxes on them are so low, the Journal reported.

A Federal Reserve report released earlier this month found the top 15 multinational companies accounted for about 80 percent of corporate offshore cash holdings. Some of the money appears to have been used so far for stock buybacks.

At those companies, which in turn had about 80 percent of their cash overseas, stock buybacks "spiked dramatically," the report said, rising to $55 billion in the first three months of 2018, up from $23 billion in the last three months of 2017, before the tax law had taken effect.

"Firms can also pay out cash to shareholders through dividends; however, unlike buybacks, dividends were little changed for the top 15 cash holders relative to the same period last year," the report's authors wrote. "Similarly, academic studies suggest that most of the repatriated funds during the 2004 tax holiday were used to fund share buybacks."

That's a reference to the 2004 American Jobs Creation Act, which temporarily slashed the tax rate on repatriated earnings from 35 percent to 5.25 percent. About 9,700 companies took advantage of the tax break, bringing back $312 billion. Fifteen companies, led by Pfizer, Merck and Hewlett-Packard, accounted for 52 percent of the repatriated money.