How Is Employment Information Reported To The Credit Bureaus

The credit bureaus to not collect information from your lenders.  It is up to the lender to report account information along with the required updates whenever any changes occur.  Your credit report will get updated with the record of your current employer only if one of your lenders reports the same.  A credit bureau maintains a record of all changes and variations that are reported to it by the various lenders which includes the variations, addressed variations and even Social Security number variations.  This is done in order to maintain a complete record of who and when made a very into your credit report.  This is also done as a security measure as change of information reported to a credit bureau for a particular credit report may be an indication for identity theft.
Usually the employment information gets updated when a person changes his job and applies to a new lender for credit.  Usually people changed jobs but do not bother to change information with existing lenders.  For example, someone may have an automobile loan running on their account.  Even though they may change not one but several jobs during the course of this loan they are not likely to report it to the lender.  As long as you do not change the information with one of your existing lenders and the lender subsequently does not reported to the credit bureau your employment information will not get updated.  However whenever you apply for a fresh credit or update the information with a lender with your employment information than your credit report will get updated with the same information as well.