Exhibit 8.3

[Letterhead of Wachtell, Lipton, Rosen & Katz]

June 20, 2023

Office Properties Income Trust

Two Newton Place

255 Washington Street, Suite 300

Newton, Massachusetts 02458

Ladies and Gentlemen:

We have acted as special counsel to the Special Committee of the Board of Trustees of Office Properties Income Trust, a Maryland real estate investment trust (“Parent”), in connection with the transactions contemplated by the Agreement and Plan of Merger, dated as of April 11, 2023 (as amended or supplemented through the date hereof, the “Agreement”), by and among Parent and Diversified Healthcare Trust, a Maryland real estate investment trust (the “Company”), pursuant to which the Company will merge with and into Parent, with Parent being the surviving entity (the “Merger”), on the terms and conditions set forth in the Agreement. In connection with the effectiveness of the Registration Statement on Form S-4 (as amended or supplemented through the date hereof, the “Registration Statement”) of Parent, including the joint proxy statement/prospectus forming a part thereof, relating to the Merger and initially filed with the Securities and Exchange Commission on May 19, 2023, you have requested our opinion as to certain U.S. federal income tax matters.

In providing our opinion, we have examined the Agreement, the Registration Statement and such other documents as we have deemed necessary or appropriate for purposes of our opinion. In addition, we have assumed that (i) the transaction will be consummated in accordance with the provisions of the Agreement and as described in the Registration Statement (and no transaction or condition described therein and affecting this opinion will be waived by any party), (ii) the statements concerning the transaction and the parties thereto set forth in the Agreement and in the Registration Statement are true, complete and correct, (iii) all documents submitted to us as originals are authentic, all documents submitted to us as copies conform to the originals, all relevant documents have been or will be duly executed in the form presented to us and all natural persons who have executed such documents are of legal capacity and (iv) all applicable reporting requirements have been or will be satisfied. If any of the above described assumptions are untrue for any reason or if the transaction is consummated in a manner that is different from the manner described in the Agreement or the Registration Statement, our opinion as expressed below may be adversely affected.

Based upon and subject to the foregoing and the exceptions, limitations, assumptions and qualifications described in the Registration Statement, it is our opinion that insofar as it summarizes U.S. federal income tax law, the discussion set forth in the Registration Statement under the captions “Material United States Federal Income Tax Consequences of the Merger” and “Material United States Federal Income Tax Consequences of the Merger to Holders of DHC Common Shares” is accurate in all material respects.

We express no opinion on any issue relating to the tax consequences of the transactions contemplated by the Agreement or the Registration Statement other than the opinion set forth above. Our opinion is based on current provisions of the Internal Revenue Code of 1986, Treasury Regulations promulgated thereunder, published pronouncements of the Internal Revenue Service and case law, any of which may be changed at any time with retroactive effect. Any change in applicable laws or the facts and circumstances surrounding the transaction, or any inaccuracy in the statements, facts, assumptions or representations upon which we have relied, may affect the continuing validity of our opinion as set forth herein. We assume no responsibility to inform Parent or any other person of any such change or inaccuracy that may occur or come to our attention.

We are furnishing this opinion solely in connection with the filing of the Registration Statement. We hereby consent to the filing of this opinion with the Securities and Exchange Commission as an exhibit to the Registration Statement, and to the references therein to us. In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended.

Very truly yours,

/s/ Wachtell, Lipton, Rosen & Katz