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The idea of taxing robots has gained steam in recent years as a possible way of curbing the spread of automation and better protecting American workers.

A decent chunk of jobs are at risk of being automated in the US.

Bill Gates called for the tax in 2017 and New York City Mayor Bill de Blasio laid out a plan for it during his short 2020 presidential run.

But a so-called "robot tax" faces significant hurdles in design and implementation.

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"Tax the rich" is now a common refrain in American politics. But could "tax the robots" ever become popular as well?

The idea of a so-called "robot tax" has gained steam in recent years, particularly after a barrage of studies that suggested automation threatens the future of a substantial chunk of jobs in the United States. The risk is especially pronounced within manufacturing, and increasingly those in white-collar positions.

One estimate from researchers at the Brookings Institution found that one in four US jobs are at high risk of being automated.

Bill Gates famously called for the tax back in 2017. New York City Mayor Bill de Blasio also laid out the framework for a type of robot taxation during his brief presidential run, calling for companies to pay five years' of payroll taxes for every job automated.

Both believed a robot tax could curb the spread of automation and add a layer of protection for American workers.

Orly Mazur, a tax law professor at Southern Methodist University who has researched the robot tax, says it could be used to stymie automation, though only temporarily.

"I believe an appropriately designed robot tax can hinder the progress of the development of automation that kills jobs," Mazur told Business Insider in an email, though noting she believes it's the wrong approach to deal with automation.

Such a tax could also conceivably create another source of federal revenue in an economy governed by more machines and fewer workers — reducing the possible disruption to the funding structures of Social Security and Medicare, which rely on payroll taxes paid by every worker and to help people find or train for new jobs.

Still, as novel as it sounds, the robot tax could take different shapes depending on its design. Employers could be slapped with charges equivalent to payroll taxes or lawmakers could limit deductions for businesses investing in technology that replaces humans.

Ryan Abbott, a professor at the University of Surrey School of Law in Britain who studies the intersection of law and technology, supports rolling back labor taxes on people and increasing them on capital investments.

"That too, I would consider a robot tax," he said.

Machines, though, have perpetually destroyed jobs throughout history and created new ones in their wake, bolstering workers' productivity for centuries and improving goods and services brought into the economy. They often displaced jobs in the short run.

Tractors, for example, cut the number of agricultural workers in the 20th century. But it created new opportunities for mechanics and engineers and fueled labor demand in factories.

What experts must wrestle with is the difficult question whether the next wave of automation and technological innovation is different from previous ones and crosses a new bridge — one that destroys jobs and never replaces them.

A study released last year from economists Daron Acemoglu and Pascual Restrepo found accelerating automation may not be fueling new labor demand and instead is holding back employment growth.

The hurdles behind a possible "robot tax"

The current American tax system, the Wall Street Journal noted, doesn't distinguish between business investments into technology that displaces US workers and equipment that increases productivity, such as a computer. Both types of spending are deducted from a corporation's tax bill.

William Gale, co-director of the Urban-Brookings Tax Policy Center says that legally defining what is a robot would be "a significant hurdle."

"If we have to define a robot for tax purposes, we have already lost the battle. It will be impossible to do without loopholes," Gale told Business Insider, offering the example of whether a self-driving car could be considered a robot.

Others echoed that as well. Andrew Yang, a Democratic presidential candidate who has centered his campaign around the economic perils of automation, said the idea was "appealing" but acknowledged it would be "difficult to administer" in a September tweet.

As it stands, the US tax system effectively encourages businesses to automate, even when it's not efficient as it reduces the amount of taxes that businesses pay on labor income, Abbott said.

But in an era of cut-throat economic competition, innovation may also be a matter of corporate survival, according to Gale.

"A firm that does not make a strategic investment in order to save its workers' jobs may well find out that a competitor is willing to make that investment and in so doing drives the first firm out of business, thus eliminating the firms' jobs anyway," Gale said.

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