If you haven't enough money left before you board a bus, you can make one more journey on this bus (but not change buses). This will create a negative balance on your card, and the card will be blocked for travel until you load money again.

If you don’t have enough money on your Oyster card (or contactless card/device) to pay for a journey in London, here’s what happens:

At the Start of Your Journey

• Tube/National Rail/DLR/London Overground: If you have a positive balance but less than the single maximum fare (also called the “maximum fare” or “entry charge”), the gates will still open. This is because the system doesn’t know where you’ll exit, so it can’t check the full fare upfront. You are allowed to travel, but you will go into a negative balance.
• Buses/Trams: You cannot tap in if you don’t have at least the single bus/tram fare (£1.80 as of 2024). The reader will show a red light and the message “Seek Assistance” or “Insufficient Funds.”

During/After Your Journey

• You will complete your journey, but when you tap out, the full fare will be deducted. This will take your balance negative.
• The negative balance is essentially a small, automatic loan from Transport for London (TfL). You must pay it back before you can use your Oyster card again.

What You Need to Do Next

1. Top Up Before You Travel Again: The next time you try to tap in (at a gate or bus reader), it will be rejected with a message like “Insufficient Funds” or “Seek Assistance.”
2. Clear the Debt: You must add enough money to both:
   • Pay