English: 1943, per the copyright notice. Note that the film itself premiered on January 5, 1943.

English: Scan via Heritage Auctions. Cropped from the original image.

English: "Copyright 1943 Paramount Pictures Inc."

English: The poster had a valid copyright notice, as seen on the bottom left corner. However, the copyright for the artwork was not renewed, as was required by American copyright law to extend/maintain protection for works published 1963 or earlier. In order to maintain copyright protection, the poster would have had to be renewed 28 years after publication, in either 1970 or 1971 (see the sections for "Artwork: Original registrations and renewals" and refer to the links to search the copyright catalogs for those years). Because it was not renewed, copyright lapsed at that time. Note that the poster art is a distinct work from the film it represents and had to be renewed separately.