Taxes are not fun but they need to be handled. Stripe & Billflow can make it easier for you, following are the steps to collect Taxes.
For more detailed configuration guides and how-tos in Stripe check out the docs here.
Start by enabling taxes on your Stripe account. You can go to https://dashboard.stripe.com/settings and add the Tax feature.
For more general tax details check out Stripe's guide here.
If you haven't been using tax before, your Stripe products need a Tax Code set.
Set product behavior to include tax, or to exclude tax.
Enable Automatic Taxes on Billfow billing page Checkout Form settings. You can also enable Tax ID to be asked on checkout there. Make sure you are on v3 or greater!
Make sure your IP and/or billing address when viewing checkout form is in a country registered in your Stripe Tax settings. You should then see the checkout automatically calculate the tax!