Knowledgebase
How to display product prices in the catalog with and without tax in Magento
By default, on product list and product details pages on the frontend the prices of products are displayed without tax. If you want to, you can show the prices with the tax included or you can show both the price prior taxation and the price with the tax included. To do this, log in to the admin panel of your Magento and go to System menu>Configuration>Tax button in the Sales section on the left>Price Display Settings panel on the right.
When you expand the panel Price Display Settings you'll see a couple of options. By default, the option Display Product Prices In Catalog is set to Excluding Tax. To show prices with tax included just set the option to Including Tax and click on the Save Config button. From the same option you can also select Including and Excluding Tax. In this case two prices will be shown for each product in the catalog; the first one will be the base price without any tax and the other one will be with tax included.
The tax, of course, is calculated based on the default address of the customer and according to the tax rules that you have set up. This applies only to registered customers with a specified address. If the registered customer hasn't specified an address yet, or the customer is a guest, the tax will be calculated using the default tax destination calculation address of the store. This address can be configured from the settings in the panel Default Tax Destination Calculation that's on the same page.
For a detailed description of all the system tax settings check out the tutorial on the system tax settings in Magento.