Apparently the answer is “yes” according to Univ. of Virginia law prof and former chief of staff of the Joint Committee on Taxation, George K. Yin. Yin writes
President Trump’s continuing refusal to release his tax returns despite the contrary common practice of presidents over the last 40 years has spurred interest in finding alternative ways to obtain the information. This article describes the authority of Congress, under section 6103(f)(1) and (4)(A), to obtain, inspect, and disclose the confidential tax information of any taxpayer, including the president, without the taxpayer’s consent. The authority may be exercised by any one of three tax committees: the House Ways and Means Committee, the Senate Finance Committee, and the Joint Committee on Taxation.
For details, see Yin’s article Congressional Authority to Obtain And Release Tax Returns, 154 Tax Notes 1013 (2017). Interesting. — Joe