I took a deduction for Aflac out of an employees check accidently and need to reimburse it so it does not show up on their w2.

Hello there, cindy141.

I'm here to help correct the deducted paycheck so it will not show in their W2. 

You can delete and recreate the check to ensure you won't have any issues moving forward.

Here's how to delete the paycheck:

1. Choose the Payroll tab from the left menu.
2. Click Employees list.
3. Under Run Payroll, hit Paycheck List.
4. Change the date range if necessary, and then click the paycheck you want to delete.
5. Click Delete.
6. Mark the tick box to confirm the deletion, and then tap Delete Paycheck.

​​​​​​​You may refer to this article: Delete or void employee paychecks.

Once done, you can now recreate the paycheck 

1. Go to Payroll menu and click Employees.
2. Choose  Employees.
3. Tap Run Payroll.
4. Hit Preview payroll.
5. Click  Preview payroll details or Submit payroll.
6. Choose Finish Payroll.
   
   

You can also check this article to know more on how QuickBooks Online calculates sales tax.

Don't hesitate to leave your questions about your employees paycheck. I'll get back to you as soon as I can.