Laravel Spark + GST

You should be able to get GST added by creating a Tax Rate in the Products section of Stripe. After that copy the Tax Rate ID and assign it to the Laravel Model that is the Billable model for Spark.

https://laravel.com/docs/10.x/billing#subscription-taxes

Alternatively since you want multiple countries, you can copy extend the Features class to have a new method called gstCollection. https://spark.laravel.com/docs/spark-stripe/taxes.html

I don't see anywhere in stripe to configure a tax rate table. When you setup a subscription it is looking for a "Product tax code" that you pick from a list - problem is it does not give you an actual code!!? To even enable that you also have to setup a Tax Registration. So all that is done, there appears to be nowhere to retrieve the code and checkout throws an error if you don't populate the taxRates array. Still searching Stripe docs for where that code might be hiding.

Maybe try enabling automatic tax: https://laravel.com/docs/10.x/billing#tax-configuration