The following link will provide you with the most up-to-date information on travel restrictions and documents required when traveling to Bulgaria:

Coronavirus – how to travel? (Bulgarian Ministry of Foreign Affairs)

Travel options and requirements – Sofia Airport

Transportation in Sofia – Official municipality information

Transport from and to the Airport 

IMPORTANT! It is recommended that you do not use taxi services offered outside the office of the taxi operator or in front of the terminal to avoid the risk of abuse.