We classify essential as an expense a client has to make to live, and desirable expenses as those that they want to make to enjoy their life.
When adding these, the amounts in the two boxes (if both are used) should equal the total amount that the client thinks that they will spend.
For example, the client thinks they'd like to spend £35,000 pa when they retire and their living expenses come to £15,000 pa. This would go into the Essential field, the further £20,000 pa would then go into the Desirable field.
