AbstractThe merit-based incentive payment system (MIPS) is a value-based payment model created by the Centers for Medicare & Medicaid Services (CMS) to promote high-value care through performance-based adjustments of Medicare reimbursements. In this cross-sectional study, we examined the participation and performance of oncologists in the 2019 MIPS. Oncologist participation was low (86%) compared to all-specialty participation (97%). After adjusting for practice characteristics, higher MIPS scores were observed among oncologists with alternative payment models (APMs) as their filing source (mean score, 91 for APMs vs. 77.6 for individuals; difference, 13.41 [95% CI, 12.21, 14.6]), indicating the importance of greater organizational resources for participants. Lower scores were associated with greater patient complexity (mean score, 83.4 for highest quintile vs. 84.9 for lowest quintile, difference, −1.43 [95% CI, −2.48, −0.37]), suggesting the need for better risk-adjustment by CMS. Our findings may guide future efforts to improve oncologist engagement in MIPS.