▁to ▁three ▁trans it ▁systems ▁at ▁a ▁time ▁on ▁to ▁their ▁Pr esto ▁card . ▁When ▁board ing , ▁rid ers ▁tap ▁the ▁pre pa id ▁card , ▁embedded ▁with ▁an ▁R F ID ▁chip , ▁on ▁to ▁a ▁reader . ▁The ▁reader ▁will ▁then ▁check ▁for ▁either ▁a ▁valid ▁trans it ▁pass , ▁or ▁automatically ▁ded uct ▁the ▁lowest ▁available ▁fare ▁from ▁the ▁card ' s ▁balance ▁stored ▁in ▁its ▁e - pur se ▁(" st ored ▁balance "). ▁GO ▁Trans it ▁and ▁Union ▁Pear son ▁Express ▁rid ers wh ose ▁far es ▁are ▁calculated ▁by ▁distance and ▁those ▁r iding ▁T TC ▁bus es ▁which ▁travel ▁into ▁the ▁City ▁of ▁Mississ aug a ▁or ▁York ▁Region which ▁require ▁an ▁extra ▁fare ▁to ▁be ▁paid ▁when ▁crossing ▁the ▁fare ▁zone ▁boundaries must ▁also ▁tap ▁their ▁cards ▁at ▁the ▁end ▁of ▁a ▁trip . ▁The ▁readers ▁can ▁display ▁one ▁of ▁several ▁messages , ▁depending ▁on ▁trans it ▁system ▁and ▁type ▁of ▁fare : ▁ ▁T TC ▁readers ▁show ▁only ▁that ▁a ▁card ▁is ▁or ▁is ▁not ▁accepted . ▁ ▁Read ers ▁for ▁most ▁other ▁local ▁systems ▁show ▁a ▁large ▁white ▁check ▁mark ▁on ▁a ▁green ▁background , ▁accompanied ▁by ▁one ▁of ▁several ▁messages . ▁For ▁a ▁month ly ▁pass , ▁the ▁exp iry ▁date ▁is ▁shown . ▁For ▁a ▁stored - bal ance ▁fare ▁at ▁initial ▁tap - on , ▁the ▁reader ▁shows ▁the ▁fare ▁dedu cted , ▁balance ▁remaining , ▁and ▁transfer ▁period ▁allowed . ▁For ▁subsequent ▁t aps ▁within ▁the ▁transfer