SaaS in Germany – How do you handle international customers?

We use Stripe + Quaderno. Quaderno does the invoice creation and adds tax lines based on customer vs business, they validate VAT numbers, make sure there is multiple evidences (billing address, IP address, bank location) and we can download a monthly report broken down by country. Stripe's Billing product does invoice creation but it lacks features when it comes to international taxes, Stripe's Checkout product can't handle tax at all last time I checked.

We could replace Quaderno, we already remove their Checkout and QuadernoJS from our frontend and use only their API in our backend, but building our own invoice creation (with history, one-off invoices, PDF export etc) is too big of a project given our small revenue.

source: running a SaaS in Germany