Every loophole has its lover.

That’s why, despite the furor that has erupted over U.S. companies adopting foreign headquarters to reduce their taxes, it is proving so difficult to fix a corporate tax system that most everyone agrees is badly broken.

Businesses complain that the high federal tax rate of 35 percent on corporations is what propels them to exploit every opportunity to shave their tax bill. And Washington is listening: Lowering that nominal rate in exchange for pruning the crop of special-interest deductions is a principle embraced by President Barack Obama and Paul D. Ryan, R-Wis., who is chairman of the House Budget Committee.

But the truth, explains Sen. Carl Levin, D-Mich., who has introduced two bills aimed at preventing U.S. firms from merging with a foreign company to avoid paying taxes, is that “businesses all want to get rid of the other guy’s tax deductions – and reduce rates.”

Manufacturers cherish faster write-offs for equipment purchases; retailers cling to the deduction for advertising. And oil and gas companies insist the industry’s health depends on the deduction for drilling expenses.

To Levin, Washington’s first priority should be what he labels “unjustified corporate tax loopholes,” deductions that he says do absolutely nothing to encourage economic productivity, but exist solely to reduce taxes.

Whether you agree that the government should subsidize gas exploration or encourage companies to invest in new machinery, Levin said, supporters can at least make a case that these deductions help the economy. Inversions, the label applied to the foreign takeovers that have captured the public’s attention partly because many Americans perceive them as unpatriotic, are mere tax dodges, he said.

With Capitol Hill stalemated, that flash of support has encouraged the Obama administration, with a push from congressional Democrats, to pursue a way to curb inversions without legislation. But even on this issue, John A. Boehner, the speaker of the House who has won Republican support to sue the president for supposedly circumventing Congress, warned the White House to work with lawmakers on ending the exodus of taxpaying corporations.

Inversions are just one of the loopholes that critics consider particularly egregious examples of gaming the system.

At the top of the list is the rule that allows U.S. multinationals to avoid paying taxes on profits until they are brought back to the United States. Microsoft, Google and Abbott Labs, for example, have managed to escape taxes on billions of dollars in foreign profits that are nonetheless invested in U.S. Treasury bonds and other government securities. The Joint Committee on Taxation estimates that the exemption on profits that are supposedly vacationing abroad costs the federal government $50 billion a year, about 1.7 percent of total revenue.

Another target involves the tax on executive stock options. Facebook is the classic example. Its co-founder, Mark Zuckerberg, had options to buy stock at 6 cents a share, which he cashed in when each share was worth $40. The options earned Zuckerberg about $5 billion, but he wasn’t the only one to benefit. Even though Facebook did not actually pay out that $5 billion, the company was nonetheless able to deduct Zuckerberg’s windfall as a business expense. According to the Senate’s Permanent Subcommittee on Investigations, this kink in the tax law permitted Facebook to take an estimated $16 billion tax deduction when the company went public and avoid paying any taxes for several years.

In the end, the fight over taxes is mostly about money. What proportion of the nation’s tax bill should corporations pay? When the corporate tax was first passed in 1909, it amounted to 1 percent of a corporation’s income. Over the years, corporate taxes accounted for an increasing share of the cash dropped into the government’s piggy bank.

In the 1950s, corporations paid for about a quarter of total federal spending, but it has generally dropped since, accounting for about a fifth in the 1960s and about 13 percent in the ’70s. That proportion has seesawed since then and now covers about 7 percent of the country’s bills.

Those who believe corporations pay too much worry that the tax burden is putting U.S. companies at a disadvantage in the world economy. “We’ve been down this road before, and we know companies will continue to do this as long as our tax rates remain the highest in the world,” Rep. David Camp, R-Mich., the chairman of the House Ways and Means Committee, said in a statement.

Some economists have pushed to eliminate the corporate tax altogether, replacing it with a tax on individual shareholders’ personal income, dividends and capital gains.

Those in the too-little camp maintain that many corporations already pay far less than their fair share. They point out there is little historical evidence that high rates have led to job loss or a sluggish economy. “The idea that lowering the corporate tax rate will lead to more investment is fundamentally wrong,” said Joseph Stiglitz, the Nobel Prize-winning economist who has carved out a strong position as a liberal critic of Democratic and Republican government actions.

This deep split means that even if lawmakers can agree on which deductions should be eliminated, they will still be divided on the question of who should benefit.

Elaine C. Kamarck, the co-chairwoman of a bipartisan coalition of businesses and organizations that support a tax overhaul, says the only way a tax bill will pass is to use any savings derived from closing corporate loopholes solely to lower the overall corporate tax rate. The companies that have joined the coalition, which include Boeing, AT&T, Verizon, Walmart and Walt Disney, have agreed to put every loophole on the table, she said, because they believe “a low enough basic tax rate is worth giving up exemptions.”

Many Democrats and advocates of a more progressive tax system recoil at the insistence any package be revenue-neutral. “It’s ridiculous to say, ‘We can’t close this loophole unless we give all this money back,’ ” said Robert S. McIntyre, director of Citizens for Tax Justice. “Everybody says we have the highest corporate tax in the world, but many corporations pay hardly anything.”

According to a study of scores of Fortune 500 companies released this year by McIntyre’s group and the Institute on Taxation and Economic Policy, the average tax rate from 2008 to 2012 on utility, gas and electric companies was 2.8 percent. The rate for the industrial machinery sector was 4.3 percent, while the telecommunications industry averaged 9.8 percent. For the aerospace and military industry, it was 19.7 percent. Dozens of corporations including Verizon, Boeing and Corning paid nothing.