function year($day, $month) {
  // ...
  return $year;
}

year($day, $month) {

  $today_day = date('d');
  $today_month = date('m');

  $year = date('y');

  if($month > $today_month) {
    return $year;
  } else if ($month < $today_month) {
    return $year + 1;
  } else {
    if($day >= $today_day) {
      return $year;
    } else {
      return $year + 1;
    }
  }

}

function year($day, $month) {
  $date  = new DateTime("{$month}/{$day}"); // defaults to current year
  $today = new DateTime();
  if ($date <= $today) {
      $today->modify('+1 year');
  }

  return $today->format('Y');
}

echo year(6, 6); // 2017
echo year(12, 12); // 2016

function year($month, $day)
 {
     $date= date('Y').'-'.$month.'-'.$day;
     if (strtotime($date) > time()) {
         return date('y');
     }
     return (date('y')+1);
 }

 echo year(12,25);   // 16

 echo year(2,25);    // 17