What does it say in the box under this label? I own my house fully and mine shows "100,00000". If you and your partner own the house half each then each bill should have "50,00000" in that box which means it is 50 % of the total bill. If it is like this then you need to pay both bills. I am not sure what last year's bill looks like, because I only got the payment statement, but in 2015 it looked quite different to this year but there was still a band across the middle with all the numbers and around the centre of the band it also showed the percentage ownership. I assume last years bill looked either like 2015 or this year's.