Missed a deadline?
Most of the time, all deadlines are final and there are no additional appeals process for additional time.
However, if you've missed an IGB-controlled deadline (listed here), you do have the option of contacting your student senator from the Columbia University Senate to plead your case. All student senators are afforded certain privileges over the IGB, but there are multiple hoops for them to cross. If you feel that the deadline you've missed is exceptional, urgent, and worthy for additional consideration to be extended for your application, you may contact them to work with the IGB on your behalf.