Forecast users, hierarchy, and quotas
Key Takeaway
A forecast user needs Allow Forecasting and the Forecasts tab, and the forecast hierarchy controls how forecasts roll up and who can view and adjust them.
Salesforce Forecasting rolls up opportunity amounts so sales teams can see expected sales for a month or quarter. Three pieces control it. Forecast users are the people allowed to use forecasting. The forecast hierarchy sets how forecasts roll up and who can view and adjust them. Quotas are the sales goals that forecasts are measured against.
What forecast users need
To use forecasting, a user needs the "Allow Forecasting" permission and access to the Forecasts tab. To access role-based forecasts in Lightning Experience, a user also needs the "View Roles and Role Hierarchy" permission.
You can grant Allow Forecasting on each user record, in the General Information section. Assigning a user to a role in the forecast hierarchy also grants it. You need the "Manage Users" and "Customize Application" permissions to enable forecast users.
Allow Forecasting is set per user rather than per profile, so you keep granular control when different jobs share a profile.
For example, imagine a sales manager and an Accounts Payable clerk who are both on the Standard User profile. Because Allow Forecasting is set per user, they can get different forecasting access.
To give users the Forecasts tab, you can add it to a Lightning app in App Manager under Navigation Items, or set the tab to "Default On" in each user profile.