In form 8938 there is a check box saying: Check this box if this is an amended or supplemental Form 8938 for the tax year.
Above that check box there is a line saying: For tax year beginning... and ending...

If I fill form 8938 with details of an account and check that check box and write that the form is for the tax year beginning 1/2011 and ending 12/2011,

Can I attach that form 8938 to the 2012 tax year to amend a 2011 account?

I read the form 8938 instructions and my understanding is that I can attach a 8938 form to the 2012 tax return to amend or add an account to a previous tax year.

Is that correct? I tried to call the IRS help line but they just say that the form is out of their scope.

Even though the instructions say that, I would prepare a Form 1040X, if, for no other reason, so you can explain why you did not submit the Form 8938 last year when you were supposed to.

Even though the instructions say that, I would prepare a Form 1040X, if, for no other reason, so you can explain why you did not submit the Form 8938 last year when you were supposed to.

I submitted form 8938 with all my accounts with the 2011 tax return. What if I want to add one account that I missed in 2011? Can I add an amended form to the 2012 tax return?

Again, the instructions say YES.

But common sense with a bureaucracy like the IRS says to submit it with a Form 1040X so you have a record of submission.

Attaching it to your 2012 return is BEGGING the IRS to LOSE it.

The IRS is very clear on this matter. Attaching a prior year Form 8938 ONLY applies to those with a fiscal year beginning between March 1 and December 21, 2010 AND if the tax return for that period was required to include Form 8938 however it was filed prior to the release of Form 8938, then, and only then, should two Forms 8938 be included with an income tax return filed for a subsequent period.

For those who DO NOT fall within this guideline (IE calendar year taxpayers or fiscal year filers who filed a return AFTER the release of Form 8938; an AMENDED tax return should be filed for the prior period accompanied by Form 8938 AND a Statement of Reasonable Cause and Prayer for Relief from Penalties.

This also assumes that in prior periods all worldwide income has been reported and FBARs and other forms filed that do not require that the filing be made pursuant to the Offshore Voluntary Compliance Initiative or Program.

If the balances being reported are less rhan $250K in total, simply request waiver of penalties in the Form 1040X.