An employer can ask anything. However whether your husband should comply is another question, and there may be laws that protect him from complying (in my state discrimination based on amrital status is prohibited so an employer asking may be illegally disriminating).
An employer CAN NOT ask you anything. In that respect, the previous answer was dead wrong.
For example, an employer can not ask you what place of worship you go to and how much you give them. An employer MAY NOT ask you for the names of all of the people that came to your house for parties over the holidays and their names, addresses and races.
So, now that we have established that an employer may NOT just ask you anything, let's look at where the lines are.
In a job application or interview, questions about your marital status are off limits. Once you are employed, in order to determine or qualify for certain benefits, the request for a marriage certificate may be deemed to be reasonable.
Tax filings, however, are privileged. And, the tax filing of your husband is not required under any reasonable circumstance. Find a good employment attorney in Denver to discuss this with before you politely point out to the employer that you have been a good employee all along and want to remain so; however their requests violate not only your privacy but also public policy.
This answer is provided for informational purposes only. Actual legal advice can only be provided in an office consultation by an attorney licensed in your jurisdiction, with experience in the area of law in which your concern lies.
Yes, an employer is allowed to ask for the documents you have mentioned. You are also allowed to refuse to provide them. You should ask why they need them because they fit the profile of a document request made to verify employee dependants who are eligible for health insurance benefits.
More employers are asking for the documents you mentioned in order to prove the number of dependants belonging to each employee in order to verify eligibility for health insurance benefits. Ask your human resources department if this is the case.
Some employees have dealt with this issue by asking if they may ink-out sensitive information (such as income amounts, or account numbers) that employers don't require in order to satisfy their documentation of dependants. Many find that this is acceptable to their employers.
At this time, most employers are not legally required to offer health insurance to employees. There are few places in our nation where employers are effectively penalized for not providing a minimum level of health insurance benefits for employees.
Employers can legally impose conditions on eligibility for health insurance benefits. Although they cannot obtain certain private information without your consent, they may make your eligibility to receive health insurance benefits conditional upon your providing evidence of eligibility by producing the documents they request.
Unlike private employers, law enforcement officials need a warrant in order to demand and take private documents, because they are government agents and are bound by the Fourth Amendment of the U.S. Constitution.