Form 941 is the Employers Quarterly Federal Tax Return, which businesses use to report income taxes and payroll taxes that they withheld from their employees wages, as well as calculate and report the employers Social Security and Medicare tax burden. The form is used to determine the amount of taxes that a business owes. Businesses need to fill out Form 941 to report federal withholdings from employees, including information such as wages, employee tips, federal income tax withholdings, employer and employee shares of Social Security and Medicare taxes, and additional Medicare tax withholdings. The form is due on a quarterly basis, with deadlines on April 30, July 31, October 31, and January 31 of each year. If a business fails to file Form 941 on time, it may result in a penalty of 5% of the tax due with that return, which can increase up to 25% . The fastest way to file Form 941 is through the federal e-File system, and businesses can also mail the form.