The Number 1 is reserved for the current world champion
The world champion is the winner of the driver's title for the year proceeding the current year. The world champion... There's more..., as an option for them to use while they defend the championship throughout the subsequent season.
They are not obligated to use No 1, but if they do, their number remains their property.
For example, Lewis Hamilton
Lewis Hamilton (No 44) is an English-born F1 driver contracted to Mercedes in 2022. See more about Lewis on our... There's more... chose to wear his 44 while defending his championships but Max Verstappen
Max Verstappen (No 1 as 2021 World Champion, otherwise No 33) is a Belgium born F1 driver, racing under a... There's more... has adorned the front of his 2022 machine with the No 1.
