When you are using Projects, Books, and Expense, the integration between the three is very useful, but not as straightforward to set up.
First thing to realise, is that the integration is via Books - i.e first projects are integrated with books, and from there the expenses are linked. To link Projects with books, first open Projects, and look for the integrations under Setup (the wrench and spanner at the top right of the screen).
From this setup screen, select Zoho Apps under Integration. This shows all active integrations as well as other potential integrations.
Note that with Zoho Books integration, you can only integrate to Zoho Books or Zoho Invoice - you cannot integrate to these applications at the same time. As the integration works on invoicing level, if you have Zoho Books, it is recommended to integrate to Books, instead of Invoice. Second note is that this integration is not available on the Free and Standard plans of Zoho Projects (for Zoho One users, this is not an issue, as you would automatically be on the Enterprise Plan). Only the portal owner can create the Zoho Books or Invoice integration, and only Admin and Managers can have access privileges.
At the time of writing this article, Zoho is still developing the integration administration. If so, please send Zoho a message asking for Projects to be integrated with Books and Expense. This can take 24 hours.
Once projects has been integrated with Books, you will need to assign a primary client to the project for the integration to work. The primary client is the customer the project is invoiced to. To do this, open the project, and navigate to the users menu. There click on Client Users, and select Add Client Company.
A new screen opens, where you can assign a new client company. Note that it is possible to have more than one client company, but only one primary client company - this is the company receiving the invoice. Enter the information of the client company, and tick the box Primary Client.
Note - you can also set up an integration with CRM - for this you need the CRM ZSC Key, which you can generate under CRM Setup, Developer Space, API's, Zoho Service Communications (ZSC). Once this integration is done, you do not need to enter the customer information, as all accounts and users can be directly imported from CRM (instead of clicking Add Client Company, you can click the three dots next to it). Once the primary client has been assigned, the integration with Books is complete. Do note that this is not an instant integration - it can take up to 24 hours for the project to appear in Books.
In Books, navigate to Timesheet menu on the left hand side. The project should now be visible in the projects list. Note that all management of the project should be executed in Zoho Projects, not in Books.
In Expense, the project can be listed once you have selected the customer for the expense (provided that customer is a primary client in one of your projects). Expenses can now be allocated to the project, and billed to the customer.
At the time of invoicing, navigate from projects to the Financial menu on the left hand side. From there you can create a new invoice.
You can select a time and expense invoice, or an expense only invoice (if you bill expenses at a different frequency). It is important to select the "Include all the unbilled expenses of the selected customer".