How to transition from ITIN to valid SSN?

This is a followup post to how to transition from a fake to valid Social Security number.  Many DREAMers may have done something brilliant by using an ITIN in the meantime, though, it was still illegal to use this number to work.  While the long term consequences of this sort of fraud by DREAMers is not known, after you are approved for DACA, given a work permit, and receive a valid for employment Social Security number, it is time to tell the Internal Revenue Service (IRS) about it.

According to the IRS, you should stop using the ITIN (you should also contact other financial institutions about this change) and use only the SS# going forward (even after your work permit expires, you should use this number for filing taxes, though, legally you should stop working after the date of expiration).  Using both numbers just messes up everything and will come to haunt you later.  The process to switch is simple.  I recommend visiting a local IRS office and doing it in person, but if that is not possible, write a letter to Internal Revenue Service, Austin, TX 73301-0057 explaining the change, along with a copy of your SS card and if you still have it, CP 565, Notice of ITIN Assignment.  If not, make sure that you write in the letter your ITIN correctly.