marriage registration form
The official document submitted to a municipal office to register a marriage in Japan.
We submitted the marriage registration form to the city hall.
婚姻届 is the more common term for the marriage registration itself; 婚姻届書 specifically refers to the physical form or document.
Standard kanji spelling for the marriage registration form.
Variant with okurigana け; less common but still seen.
Compound of 婚姻 (kon'in, 'marriage') + 届 (todoke, 'notification') + 書 (sho, 'document').