When transferring your domain into SJB you will gain 1 (one) year on the expire date, and the cost will be a year. (except .UK)
For example if the date today is October 2012 and your domain expires naturally expires on the 30th November 2012. When you transfer your domain name in, the new expire date will now be 30th November 2013. You will be billed for that extra year at the current market cost.
There are some exceptions, please review the article "Lost One Year when Transferring a Domain Name from One Registrar to Another" for more information.