When an invoice is generated and paid via account credits, the tax is not added. Why?

Problem Statement

This article explains why tax may not appear as a separate line when an invoice is paid with account credits. The behavior depends on whether tax is configured as exclusive or inclusive.

Solution

With exclusive tax, discounts and account credits are applied to the price first, then tax is applied. With inclusive tax, tax is already part of the plan price, so credits are applied to the final amount (which already includes tax). If you see no separate tax line when credits are used, it is often because tax is inclusive: the tax is already in the price, and credits simply pay that total.

More detail: Setting up price type and Tax configuration.