What is the simplest way of determining the integer number of months
between two dates?

I would like to simplify my spreadsheet which has a hard coded date in
one cell, and the following in a column:

A22=TEXT(DATE(YEAR(A21),MONTH(A21)+1,DAY(A21)),"MM MM YYYY")

I want M22 to have the number of months between A22 and M2.

Each year has 15 lines, including some headers, and when a new fiscal
year starts, I duplicate the previous one, making the spreadsheet
longer - with summary lines between the old months and the new months.


--
"In no part of the constitution is more wisdom to be found,
than in the clause which confides the question of war or peace
to the legislature, and not to the executive department."

- James Madison