How to add default taxes?

Hi proag-judy-saskt, 

Welcome to the Community. Setting up your taxes correctly in QuickBooks Online is essential to tracking your books. I'd be glad to help. 

The default tax in account and settings is to include tax, exclude tax, or out of scope tax. If this is what you're looking for, I encourage you to follow these steps.

1. Click on Gear icon
2. Select Account and settings
3. Select Advanced
4. Click on Default tax rate selection 
5. Select your preference in the drop down
6. Click on Save and Done

Let me know if you have questions, I'll be happy to help.