I've got you covered, @ARNE.
The best way to handle past contributions is to manually enter the amount when you run the next payroll. This way, the payroll deduction for each employee will be accurate. When you're ready to run the next payroll, here's how to add the amount manually:
- Sign in to your QuickBooks Online (QBO).
- Click the Payroll from the left menu, then select Employees.
- Hit Run payroll.
- Choose the employees and add the deduction amount manually.
- Select Preview payroll, then Submit payroll.
I'm adding this article to learn more about running payroll: Process or run payroll.
Just in case you want to track voluntary deductions, mandatory deductions, and company contributions in the future, you can check out this article for detailed information: Deductions and contributions.
Please let me know if you need clarification about this, or there's anything else I can do for you. I'll be standing by for your response. Have a great day.