Starting Saturday, passengers who fail to tap their transportation card when exiting the Seoul Metropolitan Subway will be charged an additional base fare on their next trip, closing a loophole that has allowed some riders to avoid full distance-based fares. Seoul Metro said Sunday the new penalty system, aimed at deterring riders from deliberately skipping the exit tag, will apply across the entire Seoul metropolitan rail network, including lines operated by other agencies such as Korail. In Korea, subway fares are based on entry and exit card taps, with the base fare covering up to 10 kilometers and an additional 100 won charged for every 5 kilometers thereafter. If a passenger fails to tap out, the system cannot verify the distance and no extra fare is added. Under the new system, passengers who fail to tap out will be charged a surcharge equal to the base fare on their next trip — 1,550 won ($1.07) for adults 19 and older, 900 won for adolescents aged 13 to 18, and 550 won for children aged 6 to 12. Since 2004, under the integrated transfer fare system in the Seoul metropolitan are