mortgage interest release

hi i have an apartment which i live in but recently bought a house with my partner - I am getting mortgage interest relief on my apartment which is my PPR for the time being (house being redone) my partner is living in the house & recently contacted revenue with his ppsn number & our joint mortgage has this month reduced due to mortgage interest relief - should we be getting that relief considering I am getting it in apartment? not sure who to contact in revenue to find out
when i move out of apart & rent it, would be alerting revenue in any event re tax obligations etc
many thanks