what is form 1120 s u s income tax return for an s corporation 
form 1120 s u s income tax return for an s corporation is a tax document that is used to report income gains losses credits deductions and other information pertaining to businesses that are registered as s corporations to the internal revenue service irs put simply form 1120 s is considered the tax return of an s corporation the form must be filed by the 15th day of the 3rd month after the corporation s tax year who needs to file irs tax form 1120 s a corporation must file form 1120 s if it elected to be an s corporation by filing form 2553 election by a small business corporation and the irs accepted the election 12an s corporation is a business entity permitted under the u s tax code it is meant for smaller companies with fewer than 100 shareholders s corporations are considered pass through entities as they don t pay corporate taxes instead they pass the tax liabilities to their individual shareholders 3the irs uses the ownership percentage detailed in form 1120 s to allocate how much profit and loss is assigned to an individual shareholder 1a shareholder s profit and loss are relatively easy to calculate if they don t see a change in the percentage of the shares they hold during the year but if the shareholder purchases sells or transfers any additional shares or holdings during the course of the year then their profit and loss must be prorated on a per share basis 1the business structure of an s corporation allows it to pass corporate income losses deductions and credits through to shareholders for federal tax purposes 4 it avoids double taxation as individual shareholders are taxed rather than the corporation 3information included on form 1120 sas noted above s corporations use form 1120 s to report the income gains losses credits and deductions along with other information to the irs each year 4the form includes pertinent business details including the remainder of the form includes other key information which is noted in the table below 5there are also a number of different schedules that are part of form 1120 s these include form 1120 s must be accompanied by schedule k 1 this schedule must be prepared for every shareholder 7 schedule k 1 identifies each individual shareholder of the s corporation and reports the portion of income profits losses credits and deductions allotted to each shareholder the information from schedule k 1 is also included on each shareholder s individual tax return 