In general, bonus amounts would be included in gross wages. However, because requirements vary by state, I’ll direct you to the Department of Labor website for Worker’s compensation, that provides a phone number for each state, as I don’t know what state you’re in and hesitate to provide a guess without more information.
Another option for you to consider, is using an online paycheck calculator that includes within it, the state rules. (You input the data, it will provide you information on what the deductions should be). This one is free: http://www.paycheckmanager.com/FreeCal/free_payroll_calculator.aspx
We provide an article with more information on Worker’s Comp. https://fitsmallbusiness.com/workers-compensation-insurance/
We recommend small businesses consider using some kind of payroll software. Here are some free/low cost options: Best Free Payroll Software for Taxes, Direct Deposit & More