Please note that "site transfer (change of hosting provider)" and "domain transfer (change of domain registrar provider)" are terms that mean two different things:
1. Changing a hosting provider would involve change of name servers and just moving your site content from one host to another. Hosting of additional already registered by you domain names is included for free in your hosting plan.
2. Domain transfer is actually change of domain registrar (the company that has registered the domain name for you and you usually pay fees to renew your domain name with them). When changing your domain registrar (transferring your domain name) the domain name is also renewed with one additional year thus a domain transfers cost the same as new domain registration or domain renewal.
Considering the above mentioned you have two options one is to just host the domain name with us which will not cost any extra fees if you have enoung addon domains left with your plan and the second is to transfer your domain name which will cost the relevant domain name transfer fee and will also extend your domain expiration date with usually 1 year.
