How to repay the deferred taxes. Employers can make the deferral payments through the Electronic Federal Tax Payment System or by credit or debit card, money order or with a check. These payments must be separate from other tax payments to ensure they applied to the deferred payroll tax balance.
https://www.irs.gov/newsroom/what-employers-need-to-know-about-repayment-of-deferred-payroll-taxes
