France validates pension "quarters" much like the U.S. system — a full French pension requires roughly 172 quarters (about 43 years) across a career, with reduced pensions otherwise. Nearly all French private-sector employees also accrue points in the mandatory Agirc-Arrco complementary scheme, which typically pays a substantial share of a French retirement.
U.S. retirement benefits normally need 40 quarters (10 years) of credits. If you split a career between the U.S. and France, 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 France 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. France's authority issues the equivalent when France covers you.
Under the U.S.–France 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 France's system. Your employer obtains a U.S. Certificate of Coverage as proof. Beyond 5 years, coverage shifts to France.
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 France credits to reach the 40-quarter (10-year) threshold for a pro-rated U.S. retirement benefit.
The agreement has been in force since 1988.
Pension taxation depends on France's domestic law and the separate U.S.–France 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.
The totalization agreement primarily coordinates the state Sécurité sociale system. Your Agirc-Arrco points remain yours under that scheme's own rules and are generally claimable from abroad at retirement — a significant, separate slice of French retirement income that many former expats forget to claim.