T-Mobile US Inc. (TMUS  ) is planning on firing all unvaccinated corporate-level workers if they do not receive at least a first dose by April, according to a memo sent to employees.

The memo was leaked to The T-Mo Report, though T-Mobile has since confirmed the authenticity of the memo's contents to members of the press.

"With the wellbeing of our community top of mind, we're asking everyone at T-Mobile to be fully vaccinated by April 2," T-Mobile writes. "Employees who have not yet taken action to receive their first dose and upload proof by February 21 will be placed on unpaid leave. Affected employees who do not become fully vaccinated and obtain a [pass to return to work] by April 2 will be separated from T-Mobile."

Currently, retail employees and a narrow slate of other positions are exempt from the company's mandate. Employees are allowed to continue to seek religious or medical exemptions as well.

While the firm is likely to take a reputational fleecing from some, T-Mobile's mandate will be hard to challenge.

While a decisive blow to federal efforts, the Supreme Court's rejection of presidential mandates doesn't reflect the attitude that courts are taking towards private entities making similar decisions. The District Court of Northern Texas' upholding of United Airlines' (UAL  ) similarly strict mandate showed that, at least when it comes to corporations and privately owned ventures, vaccine mandates are legal and enforceable.

The crux of United's defense was the inclusion of religious and medical exemptions, which provides a "backup option" for employees. Through these exemptions, United relegated unvaccinated employees to non-customer facing roles to keep them at the company.

T-Mobile's decision likely comes as a response to the Biden administration's legal defeat. Thanks to the efforts of United, and the similarities between the two companies' mandates, T-Mobile has quite the legal standing to defend its decision as well. However, whether or not employees will mount a suit remains to be seen.