Objective To examine whether high‐deductible health plans are related to patient complexity, health services use, and medical care costs among substance use treatment patients. Data Source/Study Setting Electronic health record data from Kaiser Permanente Northern California; 2007–2011. Study Design Retrospective analysis of electronic health record data of substance use treatment patients (N = 31,001). We examined relationship of patient demographics, health comorbidities, and services use and cost to deductible level: none, low ($1–$999), and high (≥$1,000). Methods Demographic, membership, diagnostic, and utilization data were merged with cost data. Utilization and costs were summarized into 6‐month intervals. Generalized estimation methods for repeated measures with logistic, Poisson, and linear regression were used. Principal Findings Substance use patients with deductible plans were younger and had less comorbidity than those without deductibles. Patients with high deductibles had lower emergency room and hospital use 12‐ to 6‐month pretreatment, but rates became similar to other groups in the 6 months immediately prior to treatment; treatment costs were similar. Conclusion Immediately prior to entering treatment, substance use patients with and without high deductibles have similar patterns of health services utilization. We discuss implications for health policy and treatment, particularly in an era of health reform.