The Biden administration has set a Jan. 4 deadline for private companies with 100 or more employees to make sure their workers are fully vaccinated, or tested weekly for COVID-19. The new rules from the Occupational Safety and Health Administration raise some questions, like, who will pay for testing or time off to get the shots?

Who pays for what under the new rules is very strategic, said Martha Casillas, a workplace safety attorney in Los Angeles.

“It’s really trying to put the onus on the employer to support vaccinations and reduce barriers to vaccinations,” she said.

So companies must provide up to four hours of paid sick time for workers to get shots. That’s on top of any sick time that’s already offered, said Alana Ackels, an employment lawyer in Dallas.

“Now, it’s a little different for the reasonable time off to recover,” she said.

If workers experience side effects for a couple of days, employers do have to give paid time off – but that can come out of regular sick time.

Employers won’t be on the hook for testing for most workers who opt out of vaccination, said Ackels.

“Which I think was a relief for a lot of businesses because this could get really expensive really fast,” she said.

Insurance and government programs usually only cover tests that are medically necessary – so employees might have to foot the bill.