This is the variable symbol you used to pay your social security as a variable payment symbol.
The 8-digit variable symbol is used for the payment of pension insurance premiums for self-employed persons, which the Social Insurance Institution assigns to the self-employed person when he/she first notifies the start of his/her activity. This is the unique identifier of the self-employed person in the records of the ČSSZ.
It is not a birth number.
If you have a mailbox, you can log in to the CSSA portal and find the variable number in the client section.
