itonewbie - I had a nice long phone discussion with an IRS agent at the IRS International Taxpayer Service Call Center. She agreed with my take on the question and instructed me to do exactly what my thinking was heading me towards: Enter the net SS benefits on form 1040 line 5a (on the 2018 return - replaces line 20a on the old form 1040) and enter -0- on line 5b (replaces 20b). She said all international 1040s are processed in Austin and that they are quite accustomed to this practice so that there would be no need to attach any reference to the US-Ireland treaty.

I also called Intuit help on how to get the software to do this. The man I talked to said there is no "button" to tell the software to put the zero in - I'll just have to override.

And to anyone following this conversation - be advised that Ireland is one of only eight countries with which the US has this arrangement. Canada is one of the other seven. Mexico is not.

Thanks again for all your thoughts on this. I've enjoyed our conversation.