Quick book and ADP payroll overlapped for 2 months. ADP 1/1/20 thru 2/29/20 QB 3/1/20 to current

Thank you for reaching out to us,@wen huang.

Let me share some insights about backdated paychecks in QuickBooks Online.

In QBO, the paycheck date will always base on the current pay period. If you wish to create a backdated paycheck, please check on these steps:

1. From the left pane, select Payroll. Then, select Employees.
2. Select Run payroll.
3. Locate the employee's name, and then select Create another check.
4. Enter all information needed.
5. Confirm the check date and pay period.
6. Click on Finish payroll.

Also, this article will help you print paychecks in QuickBooks Online Payroll.

I'm just a post away in case you have additional concerns. Have a great day and stay safe!