Question: how much tax is deducted from salary?
Answer: Starting with your salary of $40,000, your standard deduction of $12,400 is deducted (the personal exemption of $4,050 is eliminated for 2018–2025). This makes your total taxable income amount $27,600. Given that the first tax bracket is 10%, you will pay 10% tax on $9,875 of your income.