help changing from jointly to separately

Background: I'm a U.S. citizen living in the UK.  My husband is British.  After 5 years of filing "Married, filing jointly," I've been told that we don't really need to include his income and I can file "Married, filing separately."

Ok, here's my question:  I wanted to do that this year but I found something on the IRS site that suggested you have to fill out some form to change how you file FIRST.  I didn't do this before the deadline, so I went ahead and filed as I always do (jointly) for 2003.  Where is this form I need to fill out?  I found a 1040x but that seems to be to ammend past 1040's, which I don't want to do.  I just want to tell the IRS that next year I want to file separately.  And then since I'm not working, I really won't be filing at all.  Hooray!!  So which form do I need?  Anybody know?

Thank you!
Tracy

In my experience, there is no form to fie to switch your filing status.  Each year you can choose between filing jointly and filing separately right on the 1040.  Did the IRS website suggest something different for US citizens living outside the UK, because that is the only exception I can think of, that I wouldn't be aware of.