What day must Congress meet each year?

Answer 1

The Constitution originally specified the first Monday in December as the date for the minimum one meeting of Congress, but deferred to the right of Congress to alter this date, which was done.

A new Congress begins at noon on January 3 each year, and according to the 20th Amendment, they are required to meet on that date unless they otherwise assign a date. In years following a congressional election (every other year), Congress will meet January 3 to induct new Congressmen and Senators, if any. In years following a Presidential election, a joint session of Congress convenes to receive the votes of the Electoral College. If the count hasn't been completed before January 20, either the Vice President-elect (his count completed) or the sitting Speaker of the House would become President, until the count has been completed or until the House otherwise selects a President.

Otherwise, Congressional sessions are defined by the requirements of the Congress and may take place on any schedule they devise.

Answer 2

The U.S. Constitution, Article I, Section 4, Clause 2 called for Congress to meet at least once a year, on the first Monday of December. When the 20th Amendment changed the date when new Congressional terms start from March 4 to January 3 (effective 1935), it also changed the minimum one day per session when Congress must meet to January 3.