When a job posting requests salary information or earning history, what question are they really asking?
The inquiry is used to determine if the candidate is affordable. If the scope of the inquiry is expanded to cover beginning and ending salaries, it might provide an insight on how much the service of the candidate is valued by the current employer, i.e. if the candidate spent ten years on the job, and still holds the same position, and accumulated only standard cost of living raises, then the candidate may end up being passed over for someone who moved up through the ranks with appropriate salary increases. Certainly there are other reasons for this information.