President-elect Donald Trump’s proposal to offer U.S. companies a one-time tax rate of 10% to repatriate their overseas cash would bolster domestic liquidity and improve financial flexibility, but it would likely be a temporary blip without a broader reform of corporate taxes.

That’s the view of Moody’s Investors Service in a report published this week that argues that comprehensive tax reform could have the unique effect of being good for both creditors and shareholders, if it leads to lower debt levels and higher capital returns. A repatriation holiday, though, could have varying effects based on how companies use the cash.

“Where the rubber meets the road depends on company behavior,” Moody’s analyst Richard Lane, lead author of the report, told MarketWatch. “It could be helpful to both bondholders and shareholders if companies bring back cash and use it to pay down debt, or issue less debt going forward.”

The report looks back to the repatriation tax holiday from 2004 to glean lessons from the past. That program, which allowed companies to bring back cash at a tax rate of 5%, came with restrictions on how companies could spend the cash and did not attract widespread participation, Lane said.

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The Internal Revenue Service estimated that 843 of 9,700 companies with large overseas cash piles at the time brought back a total of $362 billion. Some big players, such as United Technologies Corp. US:UTX, opted not to take advantage because of the restrictions, which banned using the money for shareholder-friendly actions as a way to push companies to invest in growth initiatives and job-creating measures.

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Moody’s expects companies would take advantage this time around to the maximum extent possible, although it noted that no conditions have yet been stipulated.

“We don’t want to count the legislative chickens before they hatch, but if there were few or no restrictions and conditions, if companies had an incentive to bring back cash, I believe the vast majority would do so,” Lane said.

Total overseas cash held by rated non-financial U.S. companies. Source: Moody’s

The top five companies in terms of cash on hand today — Apple Inc. AAPL, -4.19% , Microsoft Corp. MSFT, -3.29% , Alphabet Inc. GOOG, -3.42% GOOGL, -3.45% , Cisco Systems Inc. CSCO, -2.64% and Oracle Corp. ORCL, -2.73% , according to Moody’s — brought back a total of $6.7 billion in 2004, equal to just 9% of their aggregate cash holdings at the beginning of their 2004 fiscal years. But some executives have signaled a greater willingness to take part this time. Apple Chief Executive Tim Cook, for one, has said he would move cash back it if it were not subject to U.S. corporate tax rates of 35%, which are among the highest in the world.

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Apple is one of a number of U.S. companies that have opted to borrow to reward shareholders instead of using their overseas cash, conducting a series of big corporate bond issues and using the proceeds to pay dividends and buy back shares. With interest rates at historically low levels, the company deemed it preferable to add debt to its balance sheet rather than incur a large tax bill.

Apple has the most cash overseas of any U.S. company at $230 billion, according to Moody’s, which estimates that offshore holdings for the five largest cash-holders will total $505 billion, or 86% of their total cash, by year-end. Total corporate cash held offshore by U.S. non-financial companies is expected to reach $1.3 trillion by the end of 2016.

Overseas cash held by Apple, Microsoft, Google, Cisco and Oracle. Source: Moody’s

“Absent a more comprehensive overhaul of U.S. tax laws, offshore cash will continue to grow,” attracted by lower-tax jurisdictions, the report said.

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Even if the Trump administration were to pursue immediate tax reform, the legislative process would likely take until at least the end of 2017, meaning offshore cash balances will still grow over the next year.

The credit implications of cash repatriation depend heavily on how the cash is used, Moody’s noted. Using it to boost shareholder returns in the form of buybacks and dividends is a clear negative, but using it to finance acquisitions would have more varied outcomes depending on the merits of individual deals, Moody’s said. There is the risk that companies would start to demand higher multiples from companies perceived to be newly cash-rich, which would hurt returns on capital.

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“An acquisition spree could distract management and lead to weaker business execution or acquisition integration,” Lane said.

Keeping cash on a company’s balance sheet is positive for its credit, unless activists pressure boards to return it to shareholders. Overall, as most companies that do deals tend to buy domestic competitors, having cash on hand puts it in the right location.

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Cisco is the company with the most to gain from tax reform, given about 74% of its long-term debt is scheduled to mature in the next five years, Lane said. Assuming its earnings before interest, taxes, depreciation and amortization, or Ebitda, remains flat and it repays debt as it comes due, the networking company could reduce its gross adjusted debt-to-EBITDA by 0.5 times by 2021 from 1.7 times as of September, the report said.

Oracle could reduce leverage to 2.5 times from 3.5 times as of September. Apple could reduce its leverage to 0.9 times by end 2021 from 1.3 times as of September, while Microsoft’s leverage could come down to 2.1 times from 2.7 times.