Recently a friend was seeking a career change and asked me this question:
If a job ad says to include salary requirements, do you have to?
I paused and gave it some thought. Here is my reply:

Unofficial Recruiter-type Answer:

At the applicant level, you’re really in a catch-22 situation. And no, it is not fair, but you may save yourself from wasting time & effort on positions that may be either too junior or too senior for you to consider.

If a job posting requires a salary range or a current salary, you may be removing yourself from the running by not following the application instructions. If it’s a very strict company with many regulations, this may be part of their standard process and those missing information may be disqualified. Of course, in negotiations, you are in effect showing the hand you’re playing. If at all possible it would always be better to provide an acceptable salary range as opposed to one specific number or your current salary. Now we need to look at the structure of the company.

When dealing with a Staffing Agency:

You need to let them know the minimum you would consider—what you need to pay your bills & survive without too much hardship—since as positions become available, they will come with a pay rate & often there isn’t much wiggle room (although on rare occasions there may be some). Government agencies & non-profits are also pretty upfront about salaries offered.

When dealing directly with a company:

From my limited experience in the corporate world, it’s common belief that the one to give a salary range first loses the game. Although getting an offer from the company first is ideal, giving your range does not necessarily put you at a loss. Your salary range will tell a few things about you:

1) If you are too far below the salary range, it will show a lack of confidence or perhaps you are not as experienced as it appears on your resume.
2) If you are too high above the range, it will appear unreasonable and you may appear out-of-touch with the local job market.
3) You need to have done some research to check out typical salaries for your position & level of experience in your extended local area. What the job would make in Chicago doesn’t really come into play unless you live within a reasonable commute of that city.
4) If there is any way for you to find out the range that people in similar positions are paid within the company, you will be able to place your range within or slightly exceeding the top end of their pay range, thereby placing yourself within reach.
5) If you’re dealing with a contract situation, you’ll want to evaluate what is covered by the compensation package. If health/dental/vision/vacation/401k are not covered you’ll have to calculate costs for coverage that is critical to you & factor that in as well. Thus contracting positions typically pay higher rates with no benefits.
6) Ask people you know in similar jobs if they “think W to X would be a reasonable range for Y position at Z company”—as opposed to asking them what salary they make. People love to give their opinion. Take this information & combine it with other info you’ve gathered: association newsletters, job listings, online salary calculators, etc.
Also note:
You do NOT need to blindly accept the first offer you are made. When they make you an offer, they’ve decided that from among their pool of candidates they want you. You are negotiating from a position of some power. Most offers of permanent employment allow for some room for negotiation and the first offer is seldom the very top of the range.

Enjoy a poor example:

Reaching the end of a job interview, the recruiter asked a young applicant fresh out of business school, "And what starting salary are you looking for?"
The applicant said, "In the neighborhood of $125,000 a year, depending on the benefits package."
The interviewer said, "Well, what would you say to a package of five weeks' vacation, 14 paid holidays, full medical and dental, company matching 401K to 50 percent of your salary, and a company car leased every two years?"
The applicant sat up straight and said, "Wow! Are you kidding?"
And the interviewer replied, "Yeah, but you started it."