Let’s begin with what the Constitution says on the topic. It’s nice and short: “The President shall from time to time give to Congress information of the State of the Union and recommend to their Consideration such measures as he shall judge necessary and expedient.” That’s it. There is no other mention of the term State of the Union in the Constitution. There are several things to note about this. First, it doesn’t specify any date, merely that he will do this “from time to time.” So the President can deliver the State of the Union as often or as seldom as he or she chooses. There is no requirement that it must take place before February 20 or any other date.
Second, the Constitution does not call it either a speech or an address, just that the President shall give Congress information about the State of the Union and recommend measures that the President thinks ought to be enacted. George Washington, our first President, started the tradition of delivering a speech to a joint session of Congress. John Adams, who had been Washington’s V.P. and became our second President also delivered the State of the Union as speeches. But Thomas Jefferson, our third President, thought that the spectacle of the President arriving at Congress and so forth was too kingly. So he chose to deliver it in writing. For the next 112 years, every President followed Jefferson’s model of sending a written report on the State of the Union and recommending laws that Congress should consider enacting.
In 1913 Woodrow Wilson became the first President since Adams to deliver the State of the Union as a speech before a joint session of Congress rather than as a written report. Calvin Coolidge’s address in 1923 was the first that was broadcast on radio (prior to that, the public had to read about the message to Congress in newspapers).
Another fun fact: even though that phrase “State of the Union” is right there in the Constitution, the message wasn’t called by that name until after President Franklin Roosevelt became the first President to include the phrase in the speech itself. Before then it was called either “The President’s Message to Congress” or “The Annual Message.” And that latter name continued to be the official name used in the Joint Resolution that Congress passed inviting the President to address Congress. The 1947 Joint Resolution was the first time that the event was officially referred to as the State of the Union Address. President Harry Truman’s 1947 State of the Union Address was also the first one to be broadcast on television.
One other important detail: the President is never invited to deliver the State of the Union Address in the first year of his or her term. They usually are invited to address a Joint Session in February shortly after being inaugurated, but that speech is not officially called a State of the Union Address.
And, because of the doctrine of the Separation of Powers (and the Founder’s notion that it is Congress that runs the government—not the President), the invitation to make the address must come from Congress, and it is Congress who determines the date of the address. On the other hand, the President can choose to simply send his or her message in writing, instead.
The fact that it didn’t happen by a particular date in February has absolutely no legal meaning, at all. I don’t know what plans, if any, are being discussed about a possible speech, but it seems to me unlikely we would have a typical Presidential Address to a Joint Session before next year. Because even though a whole lot of government officials have received at least one dose of Covid vaccine, it just does not seem like a good idea to cram the entire House, Senate, Supreme Court, most of the Cabinet, and a host of the usual family and dignitaries into a single room while we’re still in the middle of a deadly pandemic.