<?php
$mois = $_POST['mois'];
$year = $_POST['annee'];
$mois_act =  date("n");
$year_act =  date("Y");
if($mois < $mois_act AND $year == $year_act){
echo "eeroooorrrrr 40444404704 Houston on as un problème...";
}
else{
    echo "ok";
}
?>