How you ask matters. Start with curiosity, not accusation:

• “Can you walk me through what makes up this line this month?”
• “This total doesn’t match the balance sheet. Can you help me understand the difference?”
• “Can I see the receipts behind these charges?”
• “Who approved these discounts, and is there documentation?”

If an explanation does not hold up, or records are missing, involve the owner, the board, or an outside accountant. Do not try to investigate suspected theft alone.