For French tax residents:
A flat withholding tax of 21 %, in addition to social taxes
For non-French tax residents:
a withholding tax of 30 % subject to international tax treaties, increased to 75 % for income paid in a non-cooperative State or territory,
exempt from income tax
which is not (or was not) subject to any refund.
Indeed, starting with the income received since 1 January 2016, and only for the taxpayers established in a Member State of the European Economic Area, the withholding tax of the directors’ fees paid to non-residents is refundable, in part, if the effective income tax rate in France is below the rate applied (30 % or the conventional rate).