https://www.cnbc.com/2020/11/10/heres-when-the-results-of-the-2020-election-will-be-finalized.html
Dec. 8 — Last day for states to resolve election disputes
States must certify election outcomes at least six days before the Electoral College meets — known as the “safe harbor” deadline — if they want to avoid Congress getting involved in resolving potential disputes. That means any court challenges to state election results must be settled by Dec. 8, 2020.
If states certify election outcomes by this deadline, Congress must accept the results as valid.
Dec. 14 — Electors cast their ballots
Electors meet in their respective states to cast their ballots for president and vice president on the second Monday after the second Wednesday in December.
In every state except Nebraska and Maine, electors vote on a “winner takes all” basis, meaning whichever candidate wins the state’s presidential race receives all of the state’s electoral votes.
Electors send certificates of their vote to various officials, including Vice President Mike Pence, serving as president of the Senate.
Dec. 23 — President of the Senate receives electoral vote certificates
Pence must receive the formal electoral vote certificates no later than nine days after electors meet.
Jan. 6 — Congress counts electoral votes
The House and Senate convene for a joint session on Jan. 6 to count electoral votes. Pence presides over the process as president of the Senate and announces the results. The candidate that receives at least 270 out of 538 electoral votes becomes the next president.
Any objections to the electoral votes must be submitted in writing and signed by at least one House and one Senate member. If an objection arises, the two chambers consider the objection separately.
Jan. 20 — Inauguration Day
The president-elect and vice president-elect are sworn into office and officially become the president and vice president of the United States on Inauguration Day.