On 13 May 2020, US Treasury and the IRS released final regulations (the ‘2020 Final Regulations’) on the treatment of certain interests in corporations as stock or indebtedness. Treasury had previously published an advance notice of proposed rulemaking (ANPR) in the Federal Register on November 4, 2019. The final regulations generally affect corporations, including those that are partners of certain partnerships, when those corporations or partnerships issue purported indebtedness to related corporations or partnerships. The 2020 Final Regulations are effective on May 14, 2020 (anticipated date regulations will be published in the Federal Register).