The first sunday of the month, as stated on the official page of the Italian Ministry of Culture, the entrance in the state museums and archeological parks is free.
It won’t be possible to make any reservation and priority of access will be exclusive only for people with disabilities and pregnant women.
For the Vasari Corridor the online reservation remains mandatory, even during the days of free entry. But you won't have to pay any fare or fee of reservation.
By booking the tickets you will be allowed to visit the Corridor at the date and time selected, and at the Galleria delle Statue e delle Pitture with priority of entry.
The entrance to the Gallerie delle Statue e delle Pitture has to be made at least 2 hours before the time of the booking for the Vasari Corridor.
For additional informations regarding the visit to the Vasari Corridor we suggest to read the following article: Has the Vasari Corridor reopened? How do I visit it?