To calculate tax deductions, you need to:

1. Get a W-4 Form from each employee.
2. Calculate gross pay.
3. Calculate overtime.
4. Adjust gross pay for Social Security wages.
5. Calculate Federal Income Tax (FIT) withholding amount.
6. Calculate state and local taxes.
7. Calculate other deductions, such as health insurance, retirement plans, and wage garnishments.
8. Subtract all deductions from gross pay to get net pay.

Alternatively, you can use a tax calculator to calculate your tax deductions.

I hope that helps! Let me know if you have any other questions.