八達通
The Octopus "Automatic Add Value Service" (AAVS) is an automatic top-up Octopus method. This service allows for money to be automatically deducted from a credit card and credited to an Octopus card when the value of the Octopus card is less than zero. The credit card used must be one offered by one of 22 financial institutions that participate in AAVS. Participating banks include HSBC, Bank of China, and Hang Seng Bank. Depend on applicants' default, HK$150/250/500 is added to the card each time value is automatically added.