You've got two ways to add tax in Payment for Stripe: automatic, or your own rate.
- Automatic tax (easiest). Open Settings, go to Taxes, Gratuity & Fees, and turn on Collect tax automatically. Stripe works out the tax on each sale from your business address and tax registrations.
- Your own rate. Prefer to set your own? Create fixed Tax Rates in your Stripe Dashboard (or in the app under Tax Rates) and apply one to a charge.
Step-by-step setup, including what to finish in Stripe Tax: Automatic tax and per-product tax rates.