How do I show that Social Security is nontaxable on Form 1040 for a US citizen who is a full-time resident resident of Ireland?

itonewbie, thank you. Your answer led me to do some further digging and here is what I've come up with: 1. Pub 915, page 5, US citizens residing in eight specific countries (including Ireland) are exempt from US tax on their SS benefits. Page 6, if SS benefits are not taxable and you are reporting on 1040, you report your full net benefits on line 20a and enter -0- on line 20b. That should be the end of it. I also looked at Pub 514 Foreign Taxes for Individuals, page 7, which states "You cannot take a credit for foreign taxes paid or accrued on certain income that is excluded from US gross income" but I don't think I'd need to go this far because of my interpretation of Pub 915. I take this to include Social Security benefits excluded from US income. I did look at Form 1116 and I see a checkbox at the top for "certain income re-sourced by treaty". As for treaty disclosure, the instructions for form 8833, page 3, list exemptions from reporting, which include social security (third column, third bullet point). I did also read carefully the treaty Articles 18 and 24 as well as the related technical explanations. Article 18 states what we've already agreed upon, that a US citizen resident in Ireland is not subject to US tax on SS benefits (but is subject to Irish tax). I think that Article 24 is superfluous in this case because of what I read in Pub 915. If I'm right in this, my only problem is how to get my tax program to put a -0- on line 20b, which is a software issue. If I'm wrong, please tell me where my analysis has gone astray.

Because ff the tax treaty between the US and Ireland, it is fully taxable in Ireland, but not taxable in the US

The right to tax certain item differs by treaty based on negotiation between the US and the treaty partner.  The one with Ireland is one of those that assigns the sole right to tax social security income to the country of resident and where the article is excepted from saving clause.