You've reached the right support, tgpqb.
I'd love to help your with your concern. Let me guide you in creating bonus checks in QuickBooks Online (QBO).
In QBO, you can run payroll specific for bonus checks only. You'll just need to ensure it has the correct date for it to be included in your 2018 year-end payroll tax forms.
Please have this article handy for future reference about creating bonus checks in QuickBooks Online.
Feel free to visit us again if you need additional assistance when creating bonus checks. I'm always here to help.