I'm glad to see you here in the Community space. I can share some information about the updated tax forms for 2018.
Having an active payroll subscription allows you to have the most current and accurate rates and calculations for supported tax forms and payments in QuickBooks.
These changes will be implemented on the next payroll update (21901) which is currently scheduled for December. There isn't an exact date yet for when the tax forms for 2018 will be available, but I will update you once it is released.
For now, you can set up automatic updates to automatically receive payroll updates in QuickBooks:
Choose Update QuickBooks.
Select the Update Now tab.
Choose Get Updates.
Restart your QuickBooks for changes to take effect.