I am not sure if this is me being dense, so wanted to ask - I am buying a new house, and porting my existing mortgage across with some extra borrowing. I understand when you move and get a new mortgage you pay off the old one, with what you get from your old house, pay the agreed deposit and you may get to hold back some money from your equity. My question is whether porting changes the amount you get to hold back? Since you dont have to pay off the old mortgage? It doesnt seem like that sounds right but I really cant work out why.