Thanks for posting here in the Community. Let me help you on how to run payroll for September 2023.
In QuickBooks Online (QBO), you can still record a late or backdated paycheck when you pay your employees outside QBO. I'll assist you in recording the missed payroll for September. Proceed to the steps below.
In Payroll, go to Employees.
Choose Run payroll.
Select a payroll schedule once asked.
Edit the Pay date and Pay period.
Select your employee and then add their salary or hours worked.
The pay method should be a Paper check.
Once done, Preview and submit payroll.
Moreover, visit these links as your reference in managing your payroll inside QBO:
Here's some information that can help you as you check if your payroll will reflect for 2023 taxes, Shobha.
In 2023 taxes, your payroll will reflect based on the date indicated in your Paycheck Date. If the date in your payroll is within 2023, then it will be reflected in your taxes. Regarding whether you should edit your paper check, it's not recommended since this report will be based on your Paycheck Date, not your paper check.