I know how to do this in QuickBooks Online, jenkcpa. I'll gladly show you how.

To ensure that the retirement plan contributions are properly reported on your payroll tax forms and paychecks, let's record them accurately in QuickBooks. Here's how:

1. Go to the Payroll menu and then choose Employees.
2. Choose the employee's name.
   
3. In the Deductions & Contributions section, click Edit.
   
4. Click Add Deduction/contribution.
5. Select Retirement Plans and After-tax Roth 401(k) as the type.
6. Enter the necessary details.
7. Once done, select Save.
   

For additional insight, please refer to this article: Set up a Roth 401(k) Plan. It also contains general information about the retirement plan.

When it's time to get your employees paid, let's run payroll to ensure the retirement amounts are showing in their paychecks.

I'm only a few clicks away if you have further questions or need assistance adding after-tax in QuickBooks Online. It's our goal to keep your payroll data accurate.