This is my first time efiling after years of submitting by mail. I efiled and then printed a form 8453 and attached a brokerage statement, showing an uncovered sale that was a return of principal. I need to mail that. However, I have a statement of capitalization of real estate taxes that I mail every year with my 1040. I thought I could mail it in after efiling, but I noticed that the instructions for form 8453 say that if any statement you need to mail is not one of the ones listed on that form, then you can't efile at all. What should I do? Do I have to file an amended paper return with those attachments? Thanks.
Maybe.
Note: when you are not changing any dollar amounts on your amending 1040-X, you can leave all the lines 1-23 EMPTY.
get Form 1040-X from IRS website and mail it in with your attachments
You don't need to attach Form 1040.
Part III explanation: "submit required capitalization elections".