From Fragomen.com, 05/03/2013
Beginning May 7, 2013, employers are required to use the new version of Form I-9, dated 03/08/2013, when verifying the employment eligibility of new hires. Employers who have not done so should act now to incorporate the revised Form I-9 into their compliance procedures so that they are ready to use it by May 7.
Through May 6, employers are permitted to use the February 2, 2009 and August 7, 2009 editions of the form.
The revised edition expands Form I-9 to two fillable pages (plus the list of acceptable documents) and provides fuller explanations of many key sections of the form. It also includes several new information fields for employees to complete.