# Placeholder resources

Placeholder resources serve temporary roles on projects where the final resources remain unknown. Placeholders behave similarly to users, with a few differences discussed below.

**Bill rates**

If you assign a role or discipline to a placeholder, they inherit the account's default bill rates for that role or discipline. You can also create specific bill rates for placeholders using the [bill rates](/api/resource_management/openapi/bill_rates) API. Specify a `placeholder_resource_id` as the `user_id` parameter; no additional parameters are required.

**Custom fields**

You can create custom fields for placeholders through the application UI.

**Time entries**

Time tracking for placeholders is not available, meaning it's not possible to create or edit time entries for a placeholder. However, system-generated suggested entries are available for placeholders. When a placeholder is assigned to a project, the system generates scheduled hours based on the type of assignment and updates budget projections, allowing placeholders to be used for forecasting or projection.

Nevertheless, placeholders don't record time, and you can't make explicit time entry modifications for them. You can view system-generated time entries for placeholders through the [time entries](/api/resource_management/openapi/time-entries) API by passing the `placeholder_resource_ID` as the `user_id` parameter, similar to [assignments](/api/resource_management/openapi/assignments).

>**Note:** Expense items aren't available for placeholders. Tags for placeholders are also not supported. Use custom fields instead.