WASHINGTON, D.C. 20549 Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION FORM 10-Q ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2019 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 1-34364 OFFICE PROPERTIES INCOME TRUST (Exact Name of Registrant as Specified in Its Charter) Maryland 26-4273474 Large accelerated filer ☒ Accelerated filer ☐ ...

OFFICE PROPERTIES INCOME TRUST Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 10-K ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2018 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission file number 1-34364 (Exact Name of Registrant as Specified in Its Charter) Maryland (State of Organization) 26-4273474 (IRS Employer Identificati ...