When Does the Film "Charade" (1963) Take Place?
"Charade" is a comedy spy film written by Peter Stone with Marc Behm [adapting "The Unsuspecting Wife" (1961) by Peter Stone with Marc Behm] that released December 5th, 1963. So when is "Charade" set?
It takes place in the year:
We know this because when Regina "Reggie" Lampert first arrives in the American Embassy offices in Paris, the official portrait of United States of American President John F. Kennedy is on the wall and Kennedy was only president from his inauguration on January 20th, 1961 AD until his death on November 22nd, 1963 AD. So it must be after January of 1961 AD and before November of 1963 AD.

1963 AD
We know this because when Regina "Reggie" Lampert first arrives in the American Embassy offices in Paris, the official portrait of United States of American President John F. Kennedy is on the wall and Kennedy was only president from his inauguration on January 20th, 1961 AD until his death on November 22nd, 1963 AD. So it must be after January of 1961 AD and before November of 1963 AD.
More specifically, very early in the movie Inspector Edouard Grandpierre opens his drawer and the audience sees notes he has been taking on the case and the hand-written page has been dated at the top for "5/4/63" and the bottom for "5/4/1963". Most importantly, much later there is a close-up of a receipt-for-evidence document the Inspector created during this scene and it is dated "5/4/1963" representing May 4th, 1963 AD. The entire story takes place in less than a week so it is May of 1963 AD.
It was remade in 1978 as "Somebody Killed Her Husband" and in 2002 as "The Truth About Charlie".