Apply to the country that is your genuine main destination, assessed through the duration or purpose of the visits. For an ordinary tourist itinerary with six nights in Romania and three in Hungary, Romania would normally be responsible. If neither duration nor purpose identifies a main destination, the first Schengen country of entry determines responsibility. A trip centred on a specific business event may require an assessment beyond counting nights. Prepare a country-by-country schedule and ensure invitations and reservations match it. Your lawful residence and the consulate’s territorial jurisdiction also affect where you submit.