Payroll taxes are one of the areas that business owners could be liable for if not filed correctly and they would not be protected under corporate/LLC structure.
If you are outsourcing your payroll, you want to be careful who you use. It is critical that you work with a reputable firm that you know and trust. I’ve read horror stories about business owners having to pay huge penalties and back taxes because their payroll provided did not make the tax payments.
You want to make sure you know that the candidate is familiar with the states you operate in.
You want to make sure they know how to register in new states if you were to grow your business into new states.
Are they familiar with state withholding, municipal withholding and unemployment taxes. All could be required in your state or states in which you pay employees.
Do they know which states require you to be registered. Some states will not require you to register in that state if you only have one employee working in that state.
If you have more questions, I suggest consulting with an experienced bookkeeper.