Millions of self-employed individuals would be left out of President Donald Trump’s move to defer payroll taxes for the last four months of the year, according to tax experts.

That’s because the executive action specifically refers to taxes paid under Sec. 3101(a) of the Internal Revenue Code, which set the Social Security tax rate at 6.2 percent for those employed by someone else. There is no similar reference to Sec. 1401(a), which requires the self-employed to pay 12.4 percent on their own wages, or both the employer and employee share of Social Security taxes.

The $2 trillion March relief package allowed companies to defer their portion of Social Security payroll taxes and pay them back in stages, half by mid-2021 and the rest a year later. That included half of the 12.4 percent rate paid on self-employment income.

But the rest of the taxes that individuals who work for themselves — and earn less than six figures annually — would otherwise owe wouldn’t be deferred, either under the March law or under Trump’s memorandum, which he signed Saturday.

“Maybe they intended to do that and they just hadn’t added that in,” said Garrett Watson, senior policy analyst at the Tax Foundation. “Strictly speaking, reading the memoranda, it’s not in there.”

[Trump signs COVID-19 economic relief actions]

“There is no reference to the sections that apply to the Social Security tax on self-employed income,” Janet Holtzblatt, a senior fellow at the Urban-Brookings Tax Policy Center, wrote in an email. “Whether they realized that is another matter!”

Holtzblatt is the former unit chief for tax policy studies in the Tax Analysis Division of the Congressional Budget Office.

Watson noted that self-employed persons pay their taxes as part of after-the-fact estimates. Payroll taxes for the self-employed for Sept. 1 through Dec. 31 wouldn’t be paid until Jan. 15, 2021.

“One could argue, though, that self-employed workers already have a de facto deferral,” he said. Unlike those employed by companies, the self-employed would have to pay up on Jan. 15. The executive order doesn’t address when other workers would have to repay their deferrals, which means employers could decide to start withholding double the usual amount shortly after the first of the year.

Keith Hall, chief executive and president of the National Association for the Self-Employed, said he “would be shocked” if this “uneven playing field” remains in the eventual guidance to employers that Treasury is working on, which the agency will answer questions employers may have. Hall said barring an administrative fix, he thinks the issue would be corrected in an eventual relief bill lawmakers agree to.

Hall agreed that self-employed people do get a “de facto” deferral on their fourth-quarter payroll taxes. But they still have to be paid Jan.15. It would be better, he said, to be covered by the executive order, which doesn’t make clear when the deferral has to be repaid.

Hall also said he hopes that the unpaid taxes will be forgiven. Trump’s memorandum tasks Treasury with seeking solutions to that problem, including potential legislation, so workers won’t be on the hook for back taxes next year when the deferral period ends.

Hairdressers, taxi drivers

In February, there were 15.9 million self-employed people, according to Bureau of Labor Statistics data. In July, there were 15.5 million, a 2 percent decline. The overall labor force suffered more with 9 percent fewer people employed in July compared with February.

The top professions for the self-employed, according to the Labor Department, are child care workers, carpenters, construction laborers, hairdressers, landscapers, real estate agents, maids, management analysts and taxi drivers. Undoubtedly many would be covered under the tax deferral’s threshold of $4,000 in biweekly wages, which equates to $104,000 annually.

A Treasury Department spokesman declined to answer specific questions, noting that guidance on the deferral “is being developed.”

The order also differs from the more typical practice of phasing out a benefit rather than ending it abruptly at a certain income threshold. Under a strict interpretation of the memorandum, instead of the benefit applying to all wages up to $4,000, the directive says no one earning any more than that can get even a partial benefit. So the per-pay period benefit for someone earning $4,000 would be $248, or 6.2 percent of the total; but someone earning $4,010 would receive nothing.

“As written the guidance indicates this is a cliff rule — if an employee’s pay goes over the limit at all, the entire amount of employee [Social Security tax] must be withheld and paid over by the employer,” Ed Zollars of Kaplan Financial Education wrote in a blog post.

That’s a pretty unusual outcome in tax policy, which generally seeks a smoother transition for those earning above desired thresholds. In the March relief law, for instance, tax rebates of $1,200 were sent to individuals making $75,000 or less and $2,400 to joint filers making $150,000 or less. But the credit phased out at a 5 percent rate above those amounts. That means someone making $76,000 still got $1,150 with the full phaseout at $99,000. The benefit completely phased out for joint filers at $198,000 in adjusted gross income.

But the language is also a bit ambiguous, since it says payroll taxes would be deferred for those whose biweekly income is “generally” less than $4,000. The order also doesn’t say what would happen if someone making less than $4,000 biweekly goes over that amount in one pay period due to a bonus or overtime, Watson said.

“Hopefully, we’ll get more clarity on that” before the beginning of the deferral period on Sept. 1, he said.

Niels Lesniewski contributed to this report.