13th month and maternity leave

Can anyone who has been on maternity leave during December tell me whether the 13th month payment is paid in full by the mutuelle or whether it is at 82%/75& of salary please? I will be on maternity leave Dec, Jan, Feb and need to try and calculate my income.

I am worried that as my normal salary will be capped at a certain amount (less than I earn) it will erase my 13th month payment as this will take me even further over the cap so won't be counted. I would be punished for taking matenrity leave in December. Can anyone tell me if this is the case? My HR don't seem to know as I am the first employee to go on maternity leave at this time of year! Thank you.