In the Amsterdam public transport system (GVB), if you forget to "check out" with your card or mobile device, the system cannot calculate the actual distance traveled and will instead charge you a default "boarding fee." For a standard GVB bus or tram in 2026, this flat fee is typically €4.00, which is automatically deducted from your balance. If you are using a national "OV-chipkaart" on a regional Bus (Connexxion or EBS), the penalty can be as high as €6.00, and on NS trains, it can reach €20.00. Beyond the financial loss, your card could be temporarily blocked if you have too many "incomplete" journeys. However, there is a remedy: you can visit the official "uitcheckgemist.nl" website or use the GVB app to claim a refund. By entering your card number and details of the missed checkout, the system can often calculate the correct fare and credit the overcharged amount back to your card within a few days, provided you do so within the specified time limit (usually 62 days).