The Government Accountability Office yesterday released Tax-Exempt Sector: Governance, Transparency, and Oversight Are Critical for Maintaining Public Trust (52 pages).  Here is the part of the 1-page highlights:

Staffing trends and insufficient data have contributed to IRS being challenged in executing its oversight role. IRS has begun to increase staffing, obtain better data on tax-exempt entities, and increase its capacity to analyze and use the data it obtains. For the critical compliance issues IRS has identified, it has started special initiatives to improve compliance. States often oversee tax-exempt entities, frequently focusing on protecting the public from fraudulent activities and guarding against misuse of charitable assets. States and the IRS believe that more data sharing would make their oversight more efficient and effective. Consistent with our earlier recommendations, IRS has improved its processes for sharing its oversight data with the states, and Congress is considering expanded data sharing.