Generating and sending tax invoices to guests

I was shocked to find that booking.com does not generate and send tax invoices to our guests. Does anyone know whether booking.com at least provides tools or templates to partners so that they can easily generate a tax invoice and also send that tax invoice to a guest? I have tried to send an attachment (the tax invoice that I created as it was requested by the guest) and booking.com does not seem to allow this attachment to be sent. Has anyone worked out how to overcome this problem?