noun
disembarkation card; arrival card
Official form filled out by travelers upon entering a country, typically including personal information and customs declarations.
飛行機の中で入国申告書を記入した。
I filled out the disembarkation card on the plane.
Customs declaration form, specifically for declaring goods; 入国申告書 is a broader arrival card that may include customs information.
Compound of 入国 (entry into a country) + 申告書 (declaration form).