U.S. Citizenship and Immigration Services posted updated versions of forms in December. Starting February 21, 2017, USCIS will not accept versions of these forms that are dated earlier than December 23, 2016. Many filing fees were also updated with the new forms. If the new fee or new form are not included, your filing may be returned and/or rejected.
All USCIS forms are free and can be found here. Be sure to sign all forms where appropriate. An unsigned form may also be returned and/or rejected. Additionally, a list of filing fees for the different forms can be found here. For most forms, the filing fee increased.