BTW - If your single member LLC does have employees, if you use Quckbooks already for your business, you can purchase the payroll module for it, set it up for your particular state/location and it will guide you through all the withholdings you need to make from employee paychecks, as well as withholding matches and other things your business needs to pay to the state, local city/town if required, as well as the federal stuff.
Do note that if you are on QB 2017 or older, I don't know if you'll need to update to the 2018 version for the new tax laws.
