  When a customer overdraws their account and their balance is negative they
are assessed an overdraft fee. Americans pay approximately \$15 billion in
unnecessary overdraft fees a year, often in \$35 increments; users of the Mint
personal finance app pay approximately \$250 million in fees a year in
particular. These overdraft fees are an excessive financial burden and lead to
cascading overdraft fees trapping customers in financial hardship. To address
this problem, we have created an ML-driven overdraft early warning system
(ODEWS) that assesses a customer's risk of overdrafting within the next week
using their banking and transaction data in the Mint app. At-risk customers are
sent an alert so they can take steps to avoid the fee, ultimately changing
their behavior and financial habits. The system deployed resulted in a \$3
million savings in overdraft fees for Mint customers compared to a control
group. Moreover, the methodology outlined here can be generalized to provide
ML-driven personalized financial advice for many different personal finance
goals--increase credit score, build emergency savings fund, pay down debut,
allocate capital for investment.
