Ever wonder how the federal government knows how much you make each year? Each January, businesses are required by law to report the salaries paid to each of their employees. That amount is put onto a W2 form, which is sent to the employee to verify their earnings for the year. Many businesses mail paper copies of this form, but an increasing number of employers are making the W2 form available online -- it allows employees to file their tax returns sooner and it uses less paper. If you need a paper copy of your W2, businesses are required to mail a paper copy, which you can request in your employer's payroll office.