After you enter a domain name, the system checks whether that domain is already registered. It then offers you options for changing registrars. The process differs between Czech and foreign domains. In both cases, we have to follow the rules set by the relevant worldwide domain registries (separately for .CZ domains, .EU domains, .COM domains, etc.).
For Czech (.CZ) domains, switching registrars is free of charge. All you need to complete the transfer is an AUTH-ID code. You'll receive it automatically once you submit an order to transfer the domain (change registrars) - it's sent by email from the NIC.CZ association to the email address listed at the domain's registration. You then need to forward this code to podpora@best-hosting.cz. We'll take care of the remaining steps needed to complete the registrar change on your behalf.
The actual change for .CZ domains is processed within 24 hours in most cases. To speed things up, you can also generate the AUTH-ID code yourself directly in the central .CZ domain registry: https://www.nic.cz/whois/publicrequest/
For foreign domains, changing registrars often comes with a fee equal to a one-year renewal of the domain. At the same time, this kind of transfer extends the domain's registration by one year from its current expiration date. So you won't lose any money, since you'd have needed to renew the domain eventually anyway. Just as with .CZ domains, you'll need to send the AUTH-ID to podpora@best-hosting.cz.
Once you send the AUTH-ID, transferring a foreign domain's registrar takes up to 10 days. You should plan for some delay. For foreign domains, the AUTH-ID has to be obtained from your current registrar (it can't be generated automatically). You'll also need to request that the domain be unlocked for transfer - some registrars lock domains to prevent them from being transferred away.
You don't have to wait until your domain is about to expire to change registrars. Any domain in good standing can be transferred at any point during its registration period. The exception is the period right after a foreign domain has been transferred, when it's protected against another transfer. Likewise, for foreign domains, you can't change registrars once the domain has expired. Renewing an expired domain very often comes with an additional fee.