The renewal fees (or annuities) are due from the 2nd (before the last working day of the month of the anniversary date of the filing).
For French patents, renewal fees are due even before grant of the patent.
For French parts of European patents, renewal fees are due in France after grant of the European patent.
If you fail to pay the renewal fee in due time, the omission can be repaired if the renewal fee is paid during an additional grace period of 6 months.
This period starts from the first day of the month following the anniversary month of the filing of the application. (e.g.: for a date at the 31st of March, the grace period runs from the 1st of April to the 1st of October). The French Patent Office usually sends a notification of warning before forfeiture before the end of the grace period. Yet, the French Patent Office is under no obligation to do so.
In case of payment of the renewal fee within the 6-month grace period, the renewal fee has to be paid with a surcharge fee for late payment equal to 50% of the renewal fee due.
If the renewal fee remains unpaid at the end of the grace period, the French Patent Office sends a decision certifying forfeiture, approximately 2 months after the end of the grace period.
In case you do not contest the grounds of the decision certifying forfeiture, but you consider you are able to provide a legitimate reason for non payment of the fee, you can submit an appeal for reinstatement by written request to the General Director of the French Patent Office together with the payment of the prescribed fee (150 €), according to Articles L612-16 and R613-52 of the French Intellectual Property Code, specifying the circumstances that prevented you from paying the renewal fee before the due date.
The appeal has to be filed within two months of the hindrance ceasing to exist, which is considered by the French Patent Office as being the date of receipt of the decision certifying forfeiture.
Furthermore, the request for restitutio shall only be admissible within a period of one year from expiry of the grace period of six months given to pay the renewal fee with a surcharge fee for late payment.
The omitted renewal fee also has to be paid within two months from the hindrance ceasing to exist, at the rate in force at the time of payment.