Custom Form for Purchase Orders
Please add a purchase order form so that purchase orders can be created to support an estimate/invoice.
Creating a purchase order is not possible through Zoho Invoice since it primarily focuses on the sales cycle of your business. However, you can achieve it using Zoho Books.
Zoho Books is a super-set of Zoho Invoice and an extensive accounting application. It has every single functionality as Zoho Invoice and in addition, you can raise sales and purchase orders and much more.
You can easily upgrade your Invoice account to Books using the steps mentioned here:
If you have any queries, feel free to drop an email to support[at]zohoinvoice[dot]com