what I found on the net
I searched on google and got a few hits. They say that we have to notify IRS ITIN unit of the change. It may work without this "notifying", but I am going to do it anyway. It is just the matter of a FAX. Also, looks like there is no FORM to notify.
Regarding what I will fill in in 1040: I think I will just file on paper with my wife's SSN instead of ITIN. I tried to contact the ITIN unit to ask this question, but the line is very busy. If I get a definite answer regarding this I will post it.
This is the extract:
An alien
individual may become eligible to obtain
a SSN if, for example, such individual
has become a U.S. citizen or a
permanent U.S. resident (i.e., ‘‘green
card’’ holder), or is lawfully permitted
by INS to work in the United States.
The ITIN holder’s notification to the
IRS should state that the individual
either is eligible to have or has a SSN,
and should include the individual’s
name, address, previously-assigned ITIN
and new SSN (if available), the current
date, and the individual’s signature. This
information may be provided to the IRS
by FAX: (215) 516–3270 or by mail:
IRS, Philadelphia Service Center, ATTN:
ITIN Unit-D.P. 426, P.O. Box 447,
Bensalem, PA 19020. Questions regarding
this matter should be directed to
(215) 516–ITIN (4846) (not a toll-free
number).
This is the link: (I saw the similar stuff in few other links too, but this was the best with the address, ph. no, fax, etc.)
http://www.unclefed.com/Tax-Bulls/1996/RP96-52.PDF