It is common in Jewish parlance to say that someone is “having” or “getting” a bar mitzvah. But it doesn’t really work that way.
I love Rabbi Milder’s article on this topic. He covers it while talking about celebrating bar/bat mitzvah as adults. Here’s what he has to say.
Let’s talk about Bar/Bat Mitzvah.
No one really “has a Bar Mitzvah.” No one gets “Bat Mitzvahed.”
When a Jew turns 13, s/he becomes Bar (son) or Bat (daughter) Mitzvah (of the Commandment.) A Bar/Bat Mitzvah is one who has reached the age of majority in Judaism, the age at which the obligations of Jewish life kick in. No ceremony is required, and there is no transitive verb, “to Bar Mitzvah” someone.
On the other hand, being prepared to fulfill one’s Jewish responsibilities, and having the skills to execute one’s prerogatives as a Jewish adult, is a function of learning. At the age of 13, a Jew counts in the Minyan, the quorum required for Jewish prayer. That doesn’t make him/her competent to lead prayer. You don’t need to be a rabbi to lead prayer, but you do need to know how.
Similarly, the privilege of reading from the Torah is an honor that we grant those who have mastered a certain level of Hebrew, and trained in the art of cantillation. Chanting Torah is a beautiful skill, acquired through significant learning and practice.
That’s why we ask our children to study for years before they turn 13, so that they will be prepared to do what any adult Jew ought to be able to do: lead their congregation in worship, read from the Torah, and teach the meaning of Torah.
Of course, not all Jewish adults have those skills. Many of us never went to religious school, or never trained to be a Bar/Bat Mitzvah, or were not Jewish when we were teenagers.
But it is never too late to learn.