- max: documentation ( source)
- min: documentation ( source)
<?php
$startYear = 2014;
$currentYear = 2012;
$lastTaken = 2012;
$recurrenceYears = 3;
$useYear = MAX($startYear-1, MIN($currentYear, $lastTaken));
$nextRequirement = $useYear + ($recurrenceYears - (($useYear - $startYear) % $recurrenceYears));
echo $nextRequirement;