The Mobile Personal Identification Number or MPIN is a four-digit passcode that you will use for all your GCash transactions. This will be asked from you upon registration using USSD, Messenger, or GCash App. For your protection, do not share your MPIN, delete all messages containing your MPIN immediately, and regularly change your MPIN. Note that you cannot reuse an MPIN from your last 3 changes.