I've heard a ton of contradictory information on this topic, so I decided to look it up. Here's the timeline, compiled from the 12th and 20th Amendments plus the Congressional statute implementing those provisions: Nov 3 Each state holds an election to chose presidential and vice-presidential electors (3 U.S.C. sec. 1). If the election fails to produce a winner, the state legislature can set procedures for selecting electors (3 U.S.C. sec 2). If those procedures are set before election day, they aren't subject to challenge, but if they are set after election day, Congress can object (3 U.S.C. sec 5). ASAP The Governor notifies the National Archives of who has been chosen as electors (3 U.S.C. sec. 6). Dec 14 Electors for each state meet in their state to cast their votes (3 U.S.C. sec. 7-10). Votes are sent to the President of the Senate, which would be the current VP, if there is one, otherwise the senate president pro tem (3 U.S.C. sec 11). Extra copies are sent numerous places for safekeeping. (id.) Dec. 23 Senate President follows up regarding any missing electoral votes (3 U.S.C. sec. 12). Jan 3 New Congress is sworn in. (Const., 20th Amendment) Jan 6 Congress meets in joint session at 1:00 p.m. The Senate President opens and reads each state's votes, in alphabetical order. As each state's votes are read, an objection can be raised by one rep and one senator. The houses then separate to deliberate [for a maximum of 2 hours, 3 U.S.C. sec 17], after which a vote is taken on the objection. An objection is sustained upon a majority vote of both houses. If that doesn't happen (or if no objection is raised), the votes are counted. The Senate President then opens and reads the next state's votes (3 U.S.C. sec 15). Jan 7-11 If Congress doesn't finish counting the electoral votes on any given day, the meeting can go into recess and reconvene at 10:00 a.m. the next day. If there are still votes to count (or not count) after 4 sessions (January 6, 7, 8, 9), they start back up on Monday January 11 and continue until done -- no more recesses (3 U.S.C. sec 16). After the above process plays out, the person with a majority of electoral votes for president is certified as president-elect, and the person with the majority of electoral votes for VP is certified as VP-elect (12th Amendment). If nobody gets a majority of the presidential electoral votes, the top three candidates (or two, if only two received electoral votes) are put before the House to choose between as president-elect, with each state delegation getting one vote. If nobody gets a majority of the VP electoral votes, the top two candidates are put before the Senate to choose a VP-elect. (12th Amendment). January 20 at noon. The new President and Vice President are sworn in. If no new President has been chosen yet, the new Vice President serves as acting President (20th Amendment). If neither a President nor a Vice President has been selected, the next in line for the acting president role is the Speaker, then the President Pro Tem of the Senate, then the cabinet in a designated order (State, Treasury, Defense, AG ...). Each of these people would have to resign their position to take on the acting presidency, so there is a real chance they'd decline if it looks like it will be super-short-term (3 U.S.C. sec 19).