I came across the transfer rules provided by Namecheap domain registrar:
Regulations prohibit transferring domains that are less than 60 days old (or were transferred between registrars within the last 60 days). Please wait at least 60 days before transferring.
Expired domain names may not be released by your registrar. If your domain name expired and you are sure your registrar will release it, please contact support to initiate the transfer.
Transfer verification email will be sent to the Administrative Contact email address from email@example.com - make sure your whois information is up to date.
EPP authentication code will be required for all .com, .net, .org, .biz, .info, .mobi, .ca, .cc, .co, .in, .me, .tv, .us, .pe, .com.pe, .org.pe, .net.pe, .com.au, .net.au, .org.au and .xxx domains. Contact your current registrar to get an EPP code.
Please make sure the domain is not locked at the current registrar. Many registrars place locks without your knowledge.
For all .uk domain transfers, update your IPS tag to ENOM before submitting the transfer.
If your domain expired with your old registrar and you renewed it with them, please do not transfer it within 45 days of the previous expiry date since it will not add 1 more year to your domain name and you will lose out on the renewal fees paid to the older registrar.
To minimize the possible downtime during the transfer please check this help article (optional). There won't be any downtime if your domain is pointed to your host's custom DNS servers.
Check out our Knowledgebase for more information on transferring your domain to Namecheap.