To apply to organise a Specialised Expo, the government of the candidate country must notify the BIE of its application between 5 and 6 years before the proposed opening date of the Expo. For instance, if the proposed opening date of the Expo is 1 May 2027, the BIE may be notified any time between 1 May 2021 and 1 May 2022.
In the letter of notification to the BIE, the candidate country must mention the city, the proposed theme, the proposed dates, the duration of the Expo (a maximum of 3 months) and the legal status of the organisers including a guarantee from the government.
Once the BIE has been notified of one candidature, a six-month countdown is enacted, during which all other countries wishing to organise Specialised Expo 2027/28 may notify the BIE of their candidature. At the end of the six-month countdown, the BIE closes the candidature list.