They look at lots of information in order to assess your mortgage application. They use back office systems that we cannot see like the Hunter system to detect fraud and to assess your application they will look at; what you do for a living, how much your income is, how long you have been doing it, what your credit history is like, how much deposit are you putting down, how much money do you earn, what other finances you have in the background and how well they have been conducted.
All these bits of information will have a set amount of points within the lenders credit scoring system. If you get enough points you will pass their credit score. Simple things like declaring your landline and work telephone numbers all add up points so if they ask the question please fill in the box because it will help you pass each lenders credit score.