Note that the DateTime parameter has no effect in the result returned by DateTimeZone::getOffset($DateTime), unless, it refers to a DateTime where there is daylight savings in the referenced DateTimeZone.Ex.:<?php$timezone_brl = new DateTimeZone('America/Sao_Paulo');$timezone_eng = new DateTimeZone('Europe/London');$timezone_aus = new DateTimeZone('Australia/Brisbane');$dateTimes = [ new DateTime() , new DateTime('now', $timezone_eng) , new DateTime('now', $timezone_aus) , new DateTime('now', $timezone_brl) , new DateTime('2000-06-10', $timezone_brl) , new DateTime('2000-12-10', $timezone_brl) , new DateTime('2020-12-10', $timezone_brl)];foreach($dateTimes as $dateTime){ echo "\n" . $timezone_brl->getOffset($dateTime);}?>