Hannon Armstrong Sustainable Infrastructure Capital (NYSE: HASI) had its initial public offering on the New York Stock Exchange in late April. Investors and policymakers have increasing looked at the possibility of using Real Estate Investment Trusts (REITs) and Master Limited Partnerships (MLPs) to raise low-cost capital more efficiently for renewable energy projects. Opening the MLP structure to renewable energy projects requires legislation—currently pending in the House and Senate—but doing the same for REITs only requires a Treasury ruling. Hannon Armstrong received a Private Letter Ruling (PLR) from the IRS last year, but the contents are not publicly available yet. Hannon Armstrong won’t disclose the details of the PLR; nevertheless, for Hannon Armstrong to convert to a REIT structure, the IRS must have given assent in the PLR that solar, wind, and geothermal can be suitable REIT assets. As the IRS issues more PLRs and publishes Hannon Armstrong’s PLR, interested parties will be able to piece together details on the exact requirements for how to make renewable assets REITable.