what is the purpose of form 1120 s 
form 1120 s is the tax return for s corporations as such it is used by s corporations to report their income profits losses tax credits deductions and other information to the irs the form can be filed electronically or by mail and must be accompanied by schedule k 1 this schedule identifies individual shareholders in the s corporation along with the portion of income profit loss tax credits and deductions that are allocated to each of them 17who files form 1120 s form 1120 s is filed by s corporations the form must be filed only after the irs accepts the election of an s corporation filed by a business with fewer than 100 shareholders 1 the form may be prepared by a member of the corporation or a tax professional and must be filed electronically or by mail 