Deductions & credits

Unfortunately, at this point you this does apply to any amended returns done at this point.  This can be found in section 204 of the PATH act that established this criteria in the first place.  Here is the excerpt for the act passed in December 2015.  Note that although it exempts timely filed 2015 returns from the requirement of getting the SSN on or before the due date of the return, it doesn't exempt amendments to a 2015 return (or earlier returns) from this law.

PREVENTION   OF   RETROACTIVE   CLAIMS   OF EARNED  INCOME  CREDIT  AFTER  ISSUANCE  OF SOCIAL SECURITY NUMBER. IN GENERAL
Section  32(m)  is  amended  by  inserting  ‘‘on  or  before  the  due  date  for  filing  the  return for the taxable year’’ before the period at the end.

(b) EFFECTIVE DATE.

IN  GENERAL
Except  as  provided  in  paragraph  (2),  the  amendment  made  by  this  section  shall  apply  to  any  return  of  tax,  and  any  amendment  or  supplement  to  any  return  of  tax,  which  is  filed  after the date of the enactment of this Act.

EXCEPTION   FOR   TIMELY FILED   2015   RETURNS
The  amendment  made  by  this  section  shall  not   apply   to   any   return   of   tax   (other   than   an  amendment  or  supplement  to  any  return  of  tax)  for any  taxable  year  which  includes  the  date  of  the  enactment  of  this  Act  if  such  return  is  filed  on  or  before the due date for such return of tax.

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