Bloomberg has this: "An employer that chooses to delay payment of the employer portion of Social Security tax that otherwise would be due for the period from March 27 to Dec. 31, 2020, would need to deposit half of that delayed amount by Dec. 31, 2021, and the other half by Dec. 31, 2022, for that delayed payment of the employer portion of Social Security tax to be considered timely. "

And I found this:

"Specifically, all employer social security taxes otherwise required to be deposited between the date of enactment and December 31, 2020, are not required to be deposited on the normal deposit schedule. Instead, half of such taxes would be required to be deposited by December 31, 2021. The remaining deferred social security taxes would be required to be deposited by December 31, 2022.

The IRS is expected to revise Form 941, Employer’s Quarterly Federal Tax Return, to track the employer’s decision to defer tax deposits.  Employers must be mindful that wage payments late in 2020 might trigger a deposit requirement based on the employer’s usual deposit schedule, because the deferral is not triggered by the liability date (e.g., a payroll date on December 31) but instead by the deposit deadline (e.g., January 2, 2021).  In other words, the deadline for depositing the employer share of social security tax for wage payments made in late December 2020 is not deferred if the deposit deadline occurs in early 2021."

As usual, a developing story.