On every credit report, there's a section called "identifying information." In that section is a place to record employment history. One reason for including employment history on a credit report is to give hiring managers an easy way to verify information on a job application. Another reason is to give lenders subtle information about the character of a borrower.
When lenders examine a borrower's employment history, they're looking for stability. If you've been at the same job for years and your salary has continually risen, then you're a good prospect for credit. If you constantly jump from job to job and your salary has been erratic, that puts you in a less desirable position for lenders.
Your employment history is also a good indication of your capacity to repay credit [source: Federal Reserve Board]. A person with a low average annual salary wouldn't have the same capacity to repay a large credit card balance than someone with a higher salary.
If you apply for a mortgage, salary history is one of the most important considerations that lenders will make. Usually, you'll be asked to supply income tax forms for the past two years and current pay stubs as proof of your earnings [source: Federal Reserve Board].