I am in saudi running a small trvl agency,VAT tax here is 15% on profit not selling fare,can u add a custom tax asking how much profit,then calculat tax on profit?

I'm glad you made it here, moos-jed.

In QuickBooks Online (QBO), you can create a custom tax but can only choose between collecting the tax on sales or on purchases.

I'll show you the steps below on how to add a custom tax:

1. Go to Taxes in the left menu and click the Add tax button.
2. Choose Custom tax.
   
3. Fill out all the fields needed in the Add tax panel.
4. Click Save.
   

I'll leave you with the following articles for more information about managing tax in QBO:

• How do I set up sales GST/VAT rates and use them on forms? (International QBO)
• Applying Sales Tax to Transactions and Sales Forms
• About your sales tax agency
• Manage a tax rate change

While the option to know how much profit when adding custom tax and calculating tax on profit is not yet available, I encourage you to visit our  QuickBooks blog. From there we share the most recent updates which include new available features of the product.

Get back to me if you have other questions. I'm always happy to help you further. Keep safe and have a great rest of the day!