Well, I work for a credit agency, so I guess I can answer this one for you. As soon as you go 1 payment down on your credit account you will be put through your lender’s collection process. If you continue not to pay then after a while they will decide that you are not going to ever pay and you will be down as having defaulted on that account. At this point most banks etc. will sell your details to a debt recovery agency. Even if you eventually pay the debt off, you will have a default against your name which is held for 6 years. Of course, having defaults against your name is bad, as you will be viewed as a less reliable customer and you will not be able to get the best rates on your lending. However, it is not the end of the world. In a totally bog standard generic risk model, you will probably get more points added on for having a house or being on the electoral roll than you will have taken off for having a default.