Retired persons from within the EEA reaching the official age of retirement and covered by an E121/S1 health certificate are not liable for social security contributions and charges on their pension income.
Your liability to the social charges is restricted to investment and rental income, as well as capital gains.
Nevertheless, many retired expats in France are incorrectly assessed for liability to the social charges on their pensions.
You can read about the social charges on pension and other income at Social Charges on Pensions and Investment Income.
Those from the EEA will not be liable for compulsory health insurance contributions, as you will be covered through E121/S1 arrangements.
When you also consider that the income tax system in France is generous to those on low to middle incomes, it is no wonder that many commentators consider France a tax haven for retired persons from within the EEA and certain other countries!
Next: Early Retirees