The purpose of listing previous salary is so that they can determine how little they can pay you, or if you are out of their range.
You don't
have to disclose anything, but they don't have to hire, either. That said, there are reasonable and unreasonable requests.
HR Depts can and will do a credit check. They can and will contact your former employer, who can and will (most likely) disclose your dates of service and ending salary. It is becoming increasingly rare for former employers to discuss anything else beyond these documented numerical facts. You have to give sufficient information and permission for these checks to be performed, but they are considered routine.
The IRS will not disclose or discuss any information whatsoever with a third party who does not have signed power of attorney (on an specific IRS form). It is quite questionable for a employer to request federal tax returns and they cannot independently verify any information within them. Unless you're looking at a job with the CIA or some such requiring extensive security clearance, I would refuse and offer alternative means of providing specifics requested.*
Your "compensation" includes your room and board. You are certainly free to list or discuss your "compensation package" in addition to your salary. You should; clarifying as you need to on the form or in a letter. Salary: $xx,xxx Benefits, including housing stipend: $xx,xxx. You can very easily say "Yes, they gave you my salary, they didn't include the housing stipend when they confirmed amount $xx,xxx."
This article provides interesting insight into background checks, the why and what:
http://articles.moneycentral.msn.com/Ba ... cover.aspxOn a side note, and I am aware that you did not ask, your
complete compensation
is taxable, and the fair market value of your room and board
should be reflected on your W-2. This law is frequently misunderstood or simply ignored, but I would tread lightly. It's your employer who is breaking the law by not including this amount on your W-2, but you are breaking the law by not including this amount on your tax return, regardless. Now, there is no way for anyone to verify that you are or aren't including your room and board as "other income" on your tax return, but you want to be careful not to tell HR personnel that you're receiving non-taxable or untaxed benefits. You're not, you're just not paying your taxes. HR may understand this. I'm not trying to make you think you're in deep with IRS, it is very difficult to impossible for them to pursue taxation of this type of compensation (hence the common ignoring of the letter of the law), but you just want to be careful of your phrasing that may be interpreted as "I'm a tax-evader" by those who understand compensation.
*I had tax records requested, once, and was told that by the requester the IRS would verify the information. After several respectful attempts to find alternate methods of providing information, and informing the requester that I was aware that IRS would
not independently verify, I called the Fraud Investigator of this same company, told him what HR was doing, and that particular HR employee was fired. I also rescinded my application with that organization, including the statement that an ethical and honest HR Dept was an important job aspect.