Basel III Commonsense Approach for Small Entities Act or Basel III CASE Act - Directs the Board of Governors of the Federal Reserve System, the Federal Deposit Insurance Corporation (FDIC), and the Office of the Comptroller of the Currency, before issuing any final rule in relation to proposals they have issued for the International Basel III agreement on general risk-based capital requirements, to conduct an empirical study that includes: (1) a quantitative analysis of the rule's impact on the U.S. financial services sector, specifically community, mid-size, and regional financial institutions; and (2) a determination of the long-term impact of the rule, including changes to the current risk weight framework.

Allows any financial institution to provide information for the study voluntarily upon agency request, but prohibits agencies from requiring it.

Requires the study to be made available to the public for notice and comment.