Declaring renting a room..

Can anyone shed some light, i'm 32 and moved back in with my parents a few years ago, i pay them 300 a month and now i'm claiming back income tax, can i include this if they're my parents, also their retired and havent declared that im renting a room, im pretty sure its under the threshold anyway.. but i dont want there to be any problem if i put it down on a rent1 form... any suggestions?

Listening to Colm Rapple on the radio recently I think that you could claim for years 2005 and 2006 (four years is the most you can go back) without your parents being impacted. In years 2007 onwards this "loophole" was closed.