Staff Machine Learning Engineer, Underwriting and Credit

Block builds technology that increases access to the global economy through products including Square, Cash App, and Afterpay. The Staff Machine Learning Engineer will build and evolve underwriting and credit decisioning systems, managing the full modeling lifecycle from feature development and experimentation through deployment, monitoring, and iteration. The role also involves shaping AI-enabled engineering workflows and collaborating with cross-functional teams to ensure credit systems meet business and regulatory expectations.

Responsibilities:

• Build, evaluate, and maintain underwriting and decisioning models across Cash App Borrow and Afterpay
• Design and evolve credit decision frameworks, including the modeling, automation, and policy logic that manage credit exposure over time
• Design and run experiments to evaluate model performance, measure impact on approval rates and loss, and inform credit policy decisions
• Develop deep understanding of borrower behavior, repayment dynamics, and portfolio structure across both products, and use that to inform model design and decision logic
• Contribute analysis and perspective that inform portfolio-level decisions, including explaining model behavior, tradeoffs, and uncertainty to senior technical and business leaders
• Work across the full modeling lifecycle: problem formulation, feature engineering, training, calibration, deployment, monitoring, and iteration in production
• Build agentic engineering workflows that accelerate development, testing, and documentation
• Collaborate with Product, Engineering, Legal, Compliance, and Operations to ensure credit systems reflect business goals and regulatory expectations
• Share modeling context and approaches across teams, helping align how credit risk is measured, interpreted, and discussed
• Shape how AI developer tooling is adopted across the team, defining review practices, quality standards, and governance patterns

Requirements:

• • A Bachelor's degree in a quantitative field (e.g., Mathematics, Statistics, Physics, Computer Science)
• • 10+ years applying AI, machine learning, or statistical modeling in decisioning contexts such as credit, risk, fraud, recommendations, or similar domains
• • Experience with probabilistic models and decision systems, including calibration, score transformations, and interpretation of model outputs
• • Strong experimentation skills: you know how to design holdouts, measure lift, and evaluate models beyond aggregate metrics
• • Experience with model monitoring, degradation detection, and retraining strategies in production systems
• • Proficiency with AI-native development workflows. You use LLMs, agentic coding tools, and AI-assisted automation as a regular part of how you build and ship
• • Experience explaining modeling concepts, results, and limitations to senior stakeholders and cross-functional partners
• • Experience working across disciplines in environments with meaningful constraints
• This role is fully remote for candidates based in the US or Canada
• Advanced degrees welcome