Actual widget output
Product page or template

Say clearly whether prices include tax.

Each example below is the actual published output of the Product price tax note widget on a sample WooCommerce store with taxes enabled and Display prices in the shop set to Including tax. Stoneware mug is taxable; Gift card is set to tax status None.

Prices shown include tax.

Default settings on the Stoneware mug page: the store displays prices including tax, so the 'include tax' wording is shown.