How to Set up Compound Tax?
Step 1: To add compound tax, go to ‘Settings’ menu and select ‘Tax Types’
Step 2: Select the tax (Sales order tax or Purchase order tax) to which you want to add a compound tax by clicking the checkbox towards its left and click the ‘Edit’ icon towards its right.
Step 3: In the popup that appears, click the ‘Has Compound Tax’ button.
Step 4: Once done, click ‘Save’ button.