Business	12 Months Ended
Dec. 31, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business Office Properties Income Trust, or OPI, and its consolidated subsidiaries, or, together with OPI, we, us or our, is a real estate investment trust, or REIT, formed in 2009 under Maryland law. As of December 31, 2025, our wholly owned properties were comprised of 122 properties containing approximately 17,113,000 rentable square feet and we had a noncontrolling ownership interest of 51% in an unconsolidated joint venture that owned two properties totaling approximately 346,000 rentable square feet. Chapter 11 Bankruptcy Proceedings On October 30, 2025, or the Petition Date, OPI and certain of its subsidiaries, or the Debtors, voluntarily commenced cases, or the Chapter 11 Cases, under chapter 11 of title 11, or Chapter 11, of the United States Code, or the Bankruptcy Code, in the United States Bankruptcy Court for the Southern District of Texas, Houston Division, or the Bankruptcy Court. In connection with the filing of the Chapter 11 Cases, OPI entered into a Restructuring Support Agreement, or the RSA, with certain holders of our 9.00% senior secured notes due September 2029, or the September 2029 Notes, to implement a court-supervised financial restructuring pursuant to the transactions contemplated in the RSA. In connection with the Chapter 11 Cases, certain holders of the September 2029 Notes provided OPI with a $125,000 debtor-in-possession financing, or the DIP Facility, which was approved by the Bankruptcy Court on a final basis on February 4, 2026. See Note 9 for more information regarding the DIP Facility. The Debtors continue to operate their businesses as debtors-in-possession under the jurisdiction of the Bankruptcy Court and in accordance with the applicable provisions of the Bankruptcy Code and orders of the Bankruptcy Court. As debtors-in-possession, the Debtors are authorized to pay all debts and honor all obligations arising in the ordinary course of our business after the Petition Date. However, generally, the Debtors may not pay third-party claims or creditors on account of obligations arising before the Petition Date or engage in transactions outside the ordinary course of business without prior approval of the Bankruptcy Court. While the commencement of the Chapter 11 Cases constituted an event of default under certain of our debt agreements, enforcement of any remedies in respect of which is automatically stayed during the pendency of the Chapter 11 Cases. There are a number of risks and uncertainties associated with our bankruptcy proceedings, including, among others, that our prearranged plan of reorganization may not become effective. On April 21, 2026, the Debtors filed the Fourth Amended Joint Chapter 11 Plan of Reorganization of Office Properties Income Trust and Its Debtor Affiliates, or the Plan. On April 22, 2026, the Bankruptcy Court entered the Order Confirming Fourth Amended Joint Chapter 11 Plan of Reorganization of Office Properties Income Trust and Its Debtor Affiliates confirming the Plan. After the satisfaction or waiver of the conditions precedent to the effectiveness of the Plan, the Debtors intend to effect the transactions contemplated by the Plan and emerge from Chapter 11 protection. There are a number of risks and uncertainties associated with our bankruptcy proceedings, including, among others, that the Plan may not become effective. The Plan generally contemplates, among other things, that the following transactions and creditor treatment will be implemented: •Holders of the September 2029 Notes will convert their debt into (i) $300,000 in newly issued 10.000% senior secured notes due 2031, or the Secured Exit Notes, and (ii) up to $120,000 of Secured Exit Notes and $98,000 in newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan), or the Recovery Pool; certain holders of the September 2029 Notes will be able to elect any combination of Secured Exit Notes and reorganized common equity up to their pro rata portion of the Recovery Pool, while the non-electing holders will receive their fixed pro rata portion of the Recovery Pool; •Holders of our 3.25% Senior Secured Notes due 2027 will convert their debt into $385,000 in newly issued 8.375% senior secured notes due 2029, or the New 2029 Secured Notes, to be issued by a wholly owned subsidiary of OPI; •Holders of our 8.00% senior priority guaranteed unsecured notes due 2030, or the 2030 Notes, will receive 100% of their claims in newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan); •Our existing secured revolving credit facility and term loan will be amended and restated; •Our 9.00% Senior Secured Notes due March 2029 will be reinstated and rendered unimpaired; •Any claims under our mortgage notes will be unimpaired; •Holders of DIP Facility claims will receive (x) newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan) at a discount to Plan value of 37%; (y) in respect of the upfront fee under the DIP Facility, reorganized common equity (subject to dilution pursuant to the Plan) to be issued at a discount to Plan value of 37% and (z) in respect of the anchor capital commitment fee and the exit fee under the DIP Facility, reorganized common equity (subject to dilution pursuant to the Plan) to be issued at Plan value; •Holders of our other series of unsecured notes and certain unsecured deficiency claims will be treated as follows: ▪Holders of our other series of unsecured notes will receive their pro rata share of 6.3% of newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan), new warrants and the opportunity to participate in an equity rights offering in the aggregate amount of $35,000; ▪Holders of unsecured deficiency claims relating to the September 2029 Notes will receive their pro rata share of 5.3% of newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan); •Allowed administrative claims, priority tax claims, other secured claims, trade and vendor claims and other priority claims will be paid in full in cash or receive such other treatment reinstating such claims or rendering such claims unimpaired; •Other general unsecured claims that are allowed for $25 or less will be paid in full in cash and other general unsecured claims that are allowed for more than $25 may receive $25 in cash; and •Holders of our common shares prior to the effective date of the Plan will not receive any distribution and such common shares will be cancelled, released and discharged on the effective date of the Plan. The Plan also contemplates a new business management agreement and new property management agreements with The RMR Group LLC, or RMR, which agreements would take effect upon effectiveness of the Plan. The initial term of the new management agreements will be five years, with the annual fee under the business management agreement set at $14,000 per year for the first two years and the fees under our property management agreements being consistent with the fees under the existing property management agreement. In addition to the management fees, the Plan contemplates that we will issue to RMR, on the effective date of the Plan, 2% of the reorganized common equity, and, following the effective date of the Plan, we may issue up to an additional 8% of the reorganized common equity based on the satisfaction of certain financial tests. Our current management agreements with RMR will remain in effect during the pendency of the Chapter 11 Cases, and RMR will continue to manage our business in the ordinary course. See Note 6 for more information regarding our existing management agreements with RMR. Under the Bankruptcy Code, we may assume, modify, assign or reject certain executory contracts and unexpired leases, including, without limitation, leases of real property and equipment, subject to the approval of the Bankruptcy Court and to certain other conditions. Generally, the rejection of an executory contract or unexpired lease is treated as a pre-petition breach of such executory contract or unexpired lease and, subject to certain exceptions, relieves us from performing the future obligations under such executory contract or unexpired lease but entitles the contract counterparty or lessor to a pre-petition general unsecured claim for damages caused by such deemed breach. Generally, the assumption of an executory contract or unexpired lease requires us to cure existing monetary defaults under such executory contract or unexpired lease and provide adequate assurance of future performance. Accordingly, any description of an executory contract or unexpired lease in these financial statements including, where applicable, the express termination rights thereunder or a quantification of their obligations, must be read in conjunction with, and is qualified by, any overriding rejection rights we have under the Bankruptcy Code. The Plan has not yet become effective as of the date of issuance of these financial statements. Effectiveness of the Plan is subject to a number of conditions precedent. There can be no assurance that all conditions to the effectiveness of the Plan will be satisfied or waived, or that the Plan will become effective on the timeline currently contemplated, or at all. Going Concern Substantial doubt about our ability to continue as a going concern exists due to (1) insufficient liquidity to satisfy our obligations as they come due, (2) limited alternatives available to us to obtain debt or equity financing, (3) inability to refinance our maturing debt, and (4) the resulting Chapter 11 Cases. Our ability to continue as a going concern is contingent upon, among other things, our ability to implement the Plan and generate sufficient liquidity following the reorganization to meet our obligations, restructured debt obligations and operating needs. The transactions contemplated by the Plan are subject to certain conditions. Accordingly, no assurance can be given that the transactions described therein will be consummated. As a result, we have concluded that management’s plans at this stage do not alleviate substantial doubt about our ability to continue as a going concern. The accompanying consolidated financial statements are prepared in accordance with generally accepted accounting principles, or GAAP, applicable to a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.

As of December 31, 2025, our wholly owned properties were comprised of 122 properties containing approximately 17,113,000 rentable square feet and we had a noncontrolling ownership interest of 51% in an unconsolidated joint venture that owned two properties totaling approximately 346,000 rentable square feet.

On October 30, 2025, or the Petition Date, OPI and certain of its subsidiaries, or the Debtors, voluntarily commenced cases, or the Chapter 11 Cases, under chapter 11 of title 11, or Chapter 11, of the United States Code, or the Bankruptcy Code, in the United States Bankruptcy Court for the Southern District of Texas, Houston Division, or the Bankruptcy Court. In connection with the filing of the Chapter 11 Cases, OPI entered into a Restructuring Support Agreement, or the RSA, with certain holders of our 9.00% senior secured notes due September 2029, or the September 2029 Notes, to implement a court-supervised financial restructuring pursuant to the transactions contemplated in the RSA. In connection with the Chapter 11 Cases, certain holders of the September 2029 Notes provided OPI with a $125,000 debtor-in-possession financing, or the DIP Facility, which was approved by the Bankruptcy Court on a final basis on February 4, 2026. See Note 9 for more information regarding the DIP Facility.

The Debtors continue to operate their businesses as debtors-in-possession under the jurisdiction of the Bankruptcy Court and in accordance with the applicable provisions of the Bankruptcy Code and orders of the Bankruptcy Court. As debtors-in-possession, the Debtors are authorized to pay all debts and honor all obligations arising in the ordinary course of our business after the Petition Date. However, generally, the Debtors may not pay third-party claims or creditors on account of obligations arising before the Petition Date or engage in transactions outside the ordinary course of business without prior approval of the Bankruptcy Court.

While the commencement of the Chapter 11 Cases constituted an event of default under certain of our debt agreements, enforcement of any remedies in respect of which is automatically stayed during the pendency of the Chapter 11 Cases. There are a number of risks and uncertainties associated with our bankruptcy proceedings, including, among others, that our prearranged plan of reorganization may not become effective.

On April 21, 2026, the Debtors filed the Fourth Amended Joint Chapter 11 Plan of Reorganization of Office Properties Income Trust and Its Debtor Affiliates, or the Plan. On April 22, 2026, the Bankruptcy Court entered the Order Confirming Fourth Amended Joint Chapter 11 Plan of Reorganization of Office Properties Income Trust and Its Debtor Affiliates confirming the Plan. After the satisfaction or waiver of the conditions precedent to the effectiveness of the Plan, the Debtors intend to effect the transactions contemplated by the Plan and emerge from Chapter 11 protection. There are a number of risks and uncertainties associated with our bankruptcy proceedings, including, among others, that the Plan may not become effective.

•Holders of the September 2029 Notes will convert their debt into (i) $300,000 in newly issued 10.000% senior secured notes due 2031, or the Secured Exit Notes, and (ii) up to $120,000 of Secured Exit Notes and $98,000 in newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan), or the Recovery Pool; certain holders of the September 2029 Notes will be able to elect any combination of Secured Exit Notes and reorganized common equity up to their pro rata portion of the Recovery Pool, while the non-electing holders will receive their fixed pro rata portion of the Recovery Pool;

•Holders of DIP Facility claims will receive (x) newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan) at a discount to Plan value of 37%; (y) in respect of the upfront fee under the DIP Facility, reorganized common equity (subject to dilution pursuant to the Plan) to be issued at a discount to Plan value of 37% and (z) in respect of the anchor capital commitment fee and the exit fee under the DIP Facility, reorganized common equity (subject to dilution pursuant to the Plan) to be issued at Plan value;

▪Holders of our other series of unsecured notes will receive their pro rata share of 6.3% of newly issued shares of the reorganized common equity (subject to dilution pursuant to the Plan), new warrants and the opportunity to participate in an equity rights offering in the aggregate amount of $35,000;

The Plan also contemplates a new business management agreement and new property management agreements with The RMR Group LLC, or RMR, which agreements would take effect upon effectiveness of the Plan. The initial term of the new management agreements will be five years, with the annual fee under the business management agreement set at $14,000 per year for the first two years and the fees under our property management agreements being consistent with the fees under the existing property management agreement. In addition to the management fees, the Plan contemplates that we will issue to RMR, on the effective date of the Plan, 2% of the reorganized common equity, and, following the effective date of the Plan, we may issue up to an additional 8% of the reorganized common equity based on the satisfaction of certain financial tests. Our current management agreements with RMR will remain in effect during the pendency of the Chapter 11 Cases, and RMR will continue to manage our business in the ordinary course. See Note 6 for more information regarding our existing management agreements with RMR.

Under the Bankruptcy Code, we may assume, modify, assign or reject certain executory contracts and unexpired leases, including, without limitation, leases of real property and equipment, subject to the approval of the Bankruptcy Court and to certain other conditions. Generally, the rejection of an executory contract or unexpired lease is treated as a pre-petition breach of such executory contract or unexpired lease and, subject to certain exceptions, relieves us from performing the future obligations under such executory contract or unexpired lease but entitles the contract counterparty or lessor to a pre-petition general unsecured claim for damages caused by such deemed breach. Generally, the assumption of an executory contract or unexpired lease requires us to cure existing monetary defaults under such executory contract or unexpired lease and provide adequate assurance of future performance. Accordingly, any description of an executory contract or unexpired lease in these financial statements including, where applicable, the express termination rights thereunder or a quantification of their obligations, must be read in conjunction with, and is qualified by, any overriding rejection rights we have under the Bankruptcy Code.

The Plan has not yet become effective as of the date of issuance of these financial statements. Effectiveness of the Plan is subject to a number of conditions precedent. There can be no assurance that all conditions to the effectiveness of the Plan will be satisfied or waived, or that the Plan will become effective on the timeline currently contemplated, or at all.

Substantial doubt about our ability to continue as a going concern exists due to (1) insufficient liquidity to satisfy our obligations as they come due, (2) limited alternatives available to us to obtain debt or equity financing, (3) inability to refinance our maturing debt, and (4) the resulting Chapter 11 Cases. Our ability to continue as a going concern is contingent upon, among other things, our ability to implement the Plan and generate sufficient liquidity following the reorganization to meet our obligations, restructured debt obligations and operating needs.

The transactions contemplated by the Plan are subject to certain conditions. Accordingly, no assurance can be given that the transactions described therein will be consummated. As a result, we have concluded that management’s plans at this stage do not alleviate substantial doubt about our ability to continue as a going concern.

The accompanying consolidated financial statements are prepared in accordance with generally accepted accounting principles, or GAAP, applicable to a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business, and do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.