If your company has employees, you need to pay their employment taxes. If you are self-employed, you need to pay your own employment taxes. Employers should make these payments monthly or semi-weekly. Self-employed people should pay estimated taxes quarterly.
Employers remit these taxes to the IRS for each employee:
Withheld federal income tax
Social security
Medicare and additional Medicare tax, if applicable
Federal unemployment tax
Self-employed persons are responsible for paying both the “employer” and “employee” portion of these taxes:
Social security
Medicare