The Irish State Pension (Contributory) requires 520 paid weekly PRSI contributions — 10 years — with the amount based on your contribution average or total. The agreement lets U.S. quarters combine with PRSI weeks in both directions, and Ireland's deep employment ties with U.S. multinationals make this one of the most-used agreements per capita.
U.S. retirement benefits normally need 40 quarters (10 years) of credits. If you split a career between the U.S. and Ireland, you might fall short in each country alone. As long as you have at least 6 quarters of U.S. credits, the agreement lets you add your Ireland credits to reach eligibility — the U.S. then pays a benefit pro-rated to your U.S. credits only.
A Certificate of Coverage is the document that proves you're exempt from one country's social security. For U.S. coverage, the employer requests it from the SSA Office of Earnings & International Operations. Ireland's authority issues the equivalent when Ireland covers you.
Under the U.S.–Ireland agreement, a worker sent by a U.S. employer for 5 years or less normally stays under U.S. Social Security only and is exempt from Ireland's system. Your employer obtains a U.S. Certificate of Coverage as proof. Beyond 5 years, coverage shifts to Ireland.
Yes. If you have at least 6 quarters (about 1.5 years) of U.S. credits, the agreement lets you combine ("totalize") your U.S. and Ireland credits to reach the 40-quarter (10-year) threshold for a pro-rated U.S. retirement benefit.
The agreement has been in force since 1993.
Pension taxation depends on Ireland's domestic law and the separate U.S.–Ireland income tax treaty (if any), not the totalization agreement. The totalization agreement only governs which country's social security system covers you and how credits combine. Confirm pension taxation with a cross-border tax advisor.
Yes — 4 years alone is under the 520-week minimum, but the agreement adds your U.S. quarters to reach eligibility, yielding a pro-rated Irish pension for the Irish share. Request your PRSI contribution statement with your PPS number to confirm the weeks are on record.