Here's the steps to add a new tax in Zoho Invoice.

• Click the Settings tab.
• Click the Taxes sub-link under Currencies & Tax Settings.
• Click the New Tax button.
• Update the value of the tax percentage inside the Percentage (%)' field.
• Click the Save button.

The tax values will be automatically calculated if you add the preferred tax (with your preferred tax percentage) to the invoice. This is possible by associating the tax to the items. Following are the steps to select & add taxes to the items.

• Click the Items sub-tab under the Invoices tab.
• Select the item OR click the 'edit' link for editing the existing items to update/select the newly added tax.
• Once done, you could click the Save option.

Or you can directly associate/select the tax in the invoice.

• You could click the New Invoice button to create a new invoice OR you can edit the existing invoice.
• For the selected item, select the newly added Tax from the drop-down.
• Save the invoice which will reflect the invoice amount with the corresponding tax calculation.