To budget for future headcount and related personnel expenses (e.g., salary, benefits, taxes) in Oracle Planning 2024, the Workforce module must be enabled and configured. This module is specifically designed for detailed employee planning, including:

A. Financials: Incorrect. Financials focuses on revenue, expense, and financial statement planning at an aggregated level, not detailed headcount or personnel expenses like benefits and taxes.

B. Strategic Modeling: Incorrect. Strategic Modeling is for high-level scenario analysis (e.g., mergers, long-term strategies), not granular headcount budgeting.

C. Sales Planning: Incorrect. Sales Planning (if available as a custom module) targets sales forecasts and quotas, not employee-related expenses.

D. Workforce: Correct. Workforce enables budgeting for headcount (e.g., hiring plans) and calculates associated costs—salaries, benefits (e.g., health insurance), and taxes (e.g., payroll taxes)—with predefined and customizable options.

The Oracle documentation confirms that Workforce is the module tailored for headcount and personnel expense budgeting, making D the correct answer.