Can I add historical data to payroll QB online from the current paystub or do I have to start from the beginning?

Hello there, @redlinecarriers.

Yes, you can enter historical payroll information for the current calendar year. However, entering prior payroll data can only be done if no paycheck has been run yet.

You can follow these steps for the complete instructions.

1. Log in to your QuickBooks Online account.
2. Go to the Payroll menu.
3. Within the Employee tab, select the employee to open the information. Under How much did you pay [employee] this year?, select +Enter [year] prior pay details.
4. Enter the necessary information.

You can read through this article for additional information:  Set up a prior payroll.

If you have already paychecks created, you can contact our payroll specialist. They have tools that can help you add historical data to payroll QuickBooks Online from the current paystub. Here's how:
 

1. Go to Help at the upper-right corner.
2. Click Contact us.
3. Enter a short description of your concern. 
4. You can then choose how you want to start a conversation by choosing Chat, Callback, Call us.
   

Also, you can run your payroll reports from time to time to have a quick view of the transactions that you've created so far. You can check this article as a guide and to get more details on how you can use each report in the program: Run payroll reports.

Comment below if you have any other concerns or additional questions about QuickBooks payroll. I'm always here to help. Take care and have a good one.