ex entitlement tax implications

Hi, I would like to know the tax implications for one receiving a bonus entitlement. Say, I own 2004 shares, which means i'm entitled to a bonus of 200 shares. My total is now 2204. If I sell ALL my shares after 1 year, that would mean I pay 50% cgt. However, 200 of those shares were not held for the entire year? So how does that work?

An explanation would be much appreciated.