French VAT returns must be submitted and paid between the 15th and 24th day of the month following the reporting period. The exact date depends on the competent tax office, which depends on the location of the establishment or fiscal representative. Foreign non-established businesses need to file VAT returns by the 19th day of the month following the reporting period. If the due date falls on a Saturday, Sunday or public holiday, the date is shifted to the next working day.
Established businesses or non-EU companies registered via fiscal representative will be allocated a due date depending on their legal form and the first letter of the business name.
Official information published by the authorities about due dates and VAT return obligations for established and non-established businesses can be found (in French) here.
Regarding bank holidays in France, the authorities publish the applicable due dates every year. The following link provides the 2016 due dates.
Finally, EU businesses only supplying rental services of immoveable property that have opted to tax the property will need to file their VAT returns by the 24th of the month following the reporting period.