We are in the process of selling our house and moving to a newbuild property. We paid a £500 reservation deposit on the property when we agreed the price, and assumed that the balance would be paid at the end from the proceeds of our house sale and the increased mortgage lending. We have received a letter from the developers today confirming the sale which says they require a 10% deposit on exchange. We don't have this money laying around and I am bricking it thinking that the sale now wont go through. Is this standard practice? We haven't moved in 8 years so can't remember what happened last time. Is exchange of contracts day when the money moves anyway, or is it completion day? Are there any newbuild owners out there who can help me out on this?