Out-of-sequence (OOS) allocation, the process by which organ procurement organizations (OPOs) can deviate from standard rank lists of potential recipients to expeditiously allocate deceased-donor kidneys, is rising in the U.S. We aimed to determine whether current OPO reporting practices obscure the extent of OOS allocation. Using match-run data for all U.S. deceased-donor kidney transplants from 2021-2023, we defined "miscoded" OOS (mOOS) allocation transplants as those with use of the 799 or 898 OPO- initiated refusal codes ("other, specify") with free text responses clearly indicating OOS allocation, and compared these to "explicit" OOS (eOOS) allocation, wherein OOS transplants are appropriately coded using refusal codes 861-863. We found that the prevalence of mOOS allocation increased from 2021 (122 transplants) to 2023 (430 transplants) and accounted for 12% of all OOS transplants by 2023. Organs allocated via mOOS had a lower median KDPI than those allocated via eOOS (51% vs 55%, p <
0.01). While an increasing number of OPOs used mOOS throughout the study period, the practice remained concentrated overall, with 5 "outlier" OPOs performing 66% of mOOS allocations in 2023. These findings highlight the need for stricter oversight of organ allocation and underscore the responsibility of the OPTN to ensure proper data reporting.