The U.S. Constitution mandates that Congress convene at noon on January 3 in each odd numbered year, unless it has passed a law allowing for Congress to convene on a different day or time (20th Amendment, Section 2).

Does Senate change immediately after election?

On January 3, 2021, the U.S. Senate will convene to open the 117th Congress. ... In odd-numbered years, following congressional elections, a “new” Congress begins. From 1789 until 1934, a new Congress began on March 4. The Twentieth Amendment, adopted in 1933, changed the opening date to January.

Does the Senate change every 4 years?

Every four years the president, vice president, one-third of the Senate, and the entire House are up for election (on-year elections). On even-numbered years when there isn't a presidential election, one-third of the Senate and the whole House are included in the election (off-year elections).