New Business already paid employees before setting up quickbooks

You can enter them as a year to date payroll, @Bigods Kitchen

You can enter Prior Payroll information into QuickBooks Online (QBO) yourself as long as:

• The information being entered is within the current calendar year.
• You haven't created any current Paychecks using QBO yet.

Also, prior amounts should be entered first before running payroll in QuickBooks Online (QBO) Payroll. I recommend contacting our Payroll Support Team to guide you on how to enter the pay period.

Here's how to reach them:

1. Log in to your QuickBooks Online account.
2. Click the? Help button at the top right corner.
3. Select Contact Us.
4. Enter a brief discussion with your concern, then click Let's talk.
5. Choose the Chat or Get a callback option to talk with a live agent.

 You may reach them at your most convenient available time. For more information, check out our support hours and types.  

Let me know how it goes after contacting them. I'm always here to help. Take care.

@Bigods Kitchen 

You may record historical payroll data as Journal Entries.