[ADD] Payroll: Headcount report

closes odoo/documentation#14623

X-original-commit: aaf815f5d9
Signed-off-by: Lara Martini (larm) <larm@odoo.com>

content/applications/hr/payroll.rst

@@ -901,6 +901,7 @@ form.
    - :doc:`payroll/batches`
    - :doc:`payroll/commissions`
    - :doc:`payroll/reporting`
+   - :doc:`payroll/headcount`
    - :doc:`payroll/work_entry_analysis`
    - :doc:`payroll/payroll_localizations`
 
@@ -915,5 +916,6 @@ form.
    payroll/batches
    payroll/commissions
    payroll/reporting
+   payroll/headcount
    payroll/work_entry_analysis
    payroll/payroll_localizations

content/applications/hr/payroll/headcount.rst

@@ -0,0 +1,53 @@
+================
+Headcount report
+================
+
+The *Headcount report* in the **Payroll** app shows the number of employees on payroll and allows
+headcount comparisons between different periods of time.
+
+Create a headcount report
+=========================
+
+Create a headcount report to see the number of employees at a specific time or compare headcounts
+across periods.
+
+To create a headcount report, navigate to :menuselection:`Payroll app --> Reporting --> Headcount`
+and click :guilabel:`New`.
+
+- Report name: generated automatically as `Headcount for (Company Name) on the (YYYY-MM-DD)` and
+  **cannot** be modified.
+- :guilabel:`Company`: populated automatically (works in both single and multi-company databases)
+- :guilabel:`From`/:guilabel:`To` dates: defaults to current date (from) and blank (to). Adjust
+  these to define the period to analyze.
+
+.. image:: headcount/new-headcount.png
+   :alt: A headcount report form filled out for the third quarter of 2025.
+
+Next, click :guilabel:`Populate` to generate the report.
+
+At the top of the form, a :icon:`fa-people` :guilabel:`Employees` smart button appears. Clicking the
+button displays the total number of employees for the selected period.
+
+View all headcount reports
+==========================
+
+See how the company headcount has changed over time by viewing all headcount reports in a list view.
+
+To view all headcount reports, navigate to :menuselection:`Payroll app --> Reporting --> Headcount`.
+
+View employees in a headcount
+-----------------------------
+
+TO get an overall view of employees and their salary impact on the company, view all employee
+records of a specific headcount report.
+
+To view the employees of a specific headcount report, click the :icon:`fa-people`
+:guilabel:`Employees` smart button at the top of a headcount report.
+
+All employees from the headcount appear in a list view, grouped by :guilabel:`Department`.
+
+-  :guilabel:`Employee`: the employee's full name
+-  :guilabel:`Department`: the department their job position is in
+-  :guilabel:`Job Title`: their role
+-  :guilabel:`Employer Cost`: how much the company pays the employee each pay-period
+- :guilabel:`Wage on Payroll`: the dollar amount on payroll reports