There are various cases where a domain name may not be transferable to another Registrar. This could happen in the following circumstances:
Domain name is less than 60 days old: If the domain name you are trying to Transfer was registered less than 60 days ago, the request will get rejected by the Registry itself.
Domain name has been Transferred less than 60 days ago: A domain name can not be transferred to another Registrar within 60 days of a previous Transfer.
A domain name cannot be transferred from Registrar B to Registrar C, if it has been transferred to Registrar B from Registrar A within the last 60 days.
An exception to this rule is, the Transfer back to the previous Registrar in cases where both Registrars so agree and/or where a decision in the dispute resolution process so directs.
Theft Protection / Lock / Suspension has been applied on your domain name: If Theft Protection / Lock / Suspension has been applied on your domain name at the Current Registrar, then a Transfer for that domain name to another Registrar will not be allowed. You will first have to disable Theft Protection / Lock / Suspension for the domain name and then proceed with a Transfer.
Domain name is in the Redemption Grace Period or in the Pending Delete status: If the domain name is in either of these statuses, it can not be transferred.
If you are trying to Transfer a .EU domain name, only the 4th condition (mentioned above) will be applicable. This is because the .EU Registry does not support any Lock/Suspension feature. There is also no 60 day Registration/Transfer Lock.
A .UK domain name can be renewed upto 90 days after its Expiry, post which the domain name would be automatically deleted by the .UK Registry. There is no restriction on transferring a .UK domain name during this period. However, you need to ensure that there is sufficient time prior to Deletion, so that the domain name can be renewed with the new Registrar once the Transfer process gets completed successfully. This is because Transfer of a .UK domain name does not include one year Renewal.
Apart from this, none of conditions listed above apply to the Transfer of a .UK domain name. This is because the .UK Registry does not support any Lock/Suspension/60 day Registration or Transfer Lock and there is no concept of a Redemption Grace Period in case of a .UK domain name.
Third Level .ME domain names can not be transferred since Registrar Me-Net is the only Registrar through which Third Level .ME domain names can be registered/managed. However, no such restriction applies to Second Level .ME domain names.
A .CN domain name can not be transferred if there are less than 15 days to its Expiry. Moreover, the 2nd condition (mentioned above) will not be applicable for a .CN domain name.
The only circumstance where a .NZ domain name cannot be transferred is, when it is less than 5 days old or has a Lock applied by the Registry to it.
Only .COM.CO, .NET.CO, .NOM.CO domain names can be transferred.
.WEB.IN domain names can not be transferred.