- date: documentation ( source)
- strtotime: documentation ( source)
<?php
$date = '2020-01-04';
$myDate = date('Y-m-d', strtotime('-1 month'));
$date1 = new DateTime($myDate);
$date2 = new DateTime($date);
$interval = $date1->diff($date2);
echo "difference " . $interval->y . " years, " . $interval->m." months, ".$interval->d." days ";
if($interval->m > 3){
echo "Time is beyond 3 months";
}else{
echo "Time is not beyond 3 months";
}