CleanHTML removes the confusion between HTML and PDF invoices in WHMCS. The UI elements are placed outside the preview for better usability and HTML design can better match generated PDF.
The best place to start if you need help with a specific product is to contact the developer. All WHMCS Marketplace developers have both a website and support URL listed.
As WHMCS does provide tax rules options where you can configure your GST tax but we have some extra features in our module that makes it stand out and necessary to use.
Introduce extra billing models and charge your clients for actual server resource usage.
Send account statements to customers
Allow your clients to automatically login from Invoice Emails
Charge additional fees and set up discounts for the usage of a chosen payment gateway.