Thank you.The part that I am having difficulty with is that I had a prêt relais, which combined the amount owing on the house I was selling and provided the money for the house I was buying. Officially the old mortage ended and a certificate was issued to that effect when the pret relais started. I have read on a French finance site that the entire prêt relais can be included but for a 6 month period only and this would be most welcome. But as the crédit d'impots... only applies to a maison principal and the pret relais is straddling two houses, even though they both became my principal / sole residence when the one was sold, I am not confident to make a claim based on the entire pret relais amount. I have visited the impots twice and pretty much what you posted above was explained to me ( but thank you [:) It was just on the finer points that we ended up confusing each other.[:$] eg can I use the entire pret relais amount or only the part that I actually paid for the purchase of the new house? I am just revisiting the terms and conditions of the paprework we completed but I think that the monthly repayments we made when the Prêt relais was in operation were solely interest payments. I just want to discover how much of this monthly interest I can include.