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Debit Card security for online purchases

Simple, convenient and safe from fraud

We work hard to make your online purchases simple, convenient and safe from fraud. Your Citi Debit Card uses Mastercard® SecureCode as a quick and sophisticated way of identifying yourself to Citi Security when shopping online.

Mastercard SecureCode uses One Time Passwords as an enhanced way of authenticating certain transactions, helping to protect you from card fraud.

Holders of a Mastercard Citi Debit Card are automatically registered with Mastercard SecureCode.

To ensure you receive a One Time Password, it’s vital your current mobile number is registered with Citi.

How it works +

  • Mastercard monitors the security of your card 24 hours a day, 7 days a week. Each time you make an online purchase, the details are automatically checked against your usual spending patterns and the device(s) you use.
  • Regular, recognisable purchases may be authorised at once, to make using your card as convenient as possible. For some transactions Mastercard SecureCode may ask you to enter a One Time Password as an extra level of security.
  • Each One Time Password has six digits, and will be sent by text from ‘Citibank’ to the mobile phone you have registered with Citi.
  • To authenticate the purchase, enter the One Time Password in the on-screen box and press Submit. You will then be returned to the retailer’s site to complete your purchase.

Please make sure we have your current mobile number

The last four digits of the mobile number we hold for you are displayed at the top of the Mastercard SecureCode box.

If you haven’t registered your mobile number with us, or if you think the number we have for you is out of date, please contact CitiPhone on 0800 00 55 00 to update your mobile phone number, or +44 207 500 55 00 if calling from outside the UK.

How it works -