Since you've already filed your tax return you'll have to wait until you know if your return has been accepted or rejected, probably near the end of February. If it's rejected you can modify it to report the corrected 1099-R and then e-file it again (after correcting other errors). However, if it's accepted then you'll have to file an amended tax return (1040-X), but only after your original tax return has been processed by the IRS. Here are the instructions for filing an amended tax return:
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Was tax withheld on box 4?
If not, then NOTHING other then the box 1 and 2a amounts are even part of your tax return. The payers ID is only necessary to credit Federal tax withheld to your account and the IRS gets a copy of the corrected 1099-R also so amending might not be necessary unless the IRS send you a letter requesting it.
What you actually filed may already have the correct number in it (if you entered the data for that form in your taxes when you filed ). Especially if you used the same software last year, a DFAS 1099-R form with all teh info except the $$ in the boxes, may have transferred over from last year with the correct FEIN number already in it...
Yeah..DFAS did send out corrected forms for that number: