By Margaret Steen, for Yahoo! HotJobs

At some point during your job search, you will likely be asked about your salary history -- how much you're making at your current job, and how much you made previously. Should you tell? Is there any way to avoid telling? And why do potential employers want to know, anyway?

When forming a response to these questions, it helps to understand employers' reasons for asking.

Employers tend to use your past pay as a gauge of your market value, says Richard Phillips, a career coach and owner of Advantage Career Solutions in Palo Alto, California. They also want a sense of what salary you'll be expecting. If it's tens of thousands of dollars more than the employer can pay for the position, it's probably not worth wasting your time or the employer's on further discussions.

"It's a way to figure out if we are all playing in the same league," Phillips says.

Play Your Cards Right

Of course, this information also gives the employer a leg up in the salary negotiation process. "We're going to play poker," Phillips says. "You're going to show every other card of yours, and I'm not going to show any of my cards."

Because of this, Phillips recommends not offering salary history in an initial written application. If you're filling out an application, put dashes in the box for salary history, indicating that you saw it, he says. If you're responding to a job posting that says to send in a resume and salary history, just send the resume. If the employer is interested, someone will call to ask for more information.

"Then you're in a dialogue," Phillips says. At this point, instead of telling the employer your current or past salary, ask what range they expect to pay for the position. You could also offer to provide your desired salary range.

The Strategy Could Backfire

This approach does have pitfalls. First, some employers may not call, choosing instead to focus on applicants who provided the information on the application.

"My take on it is that if you are a qualified candidate and they are going to ignore you because you did not send in your salary history, you do not want to work for that organization," Phillips says.

Even if you make it to the conversation stage, simply stating your expectations may not work.

Tell the Truth

"They could say any number for an expectation," says Lori Itani, an independent staffing consultant who focuses on high tech companies. When Itani talks to candidates, she asks for their salary history. "Everybody I talk to ends up giving that information out," she says.

Itani is looking not only at whether the candidate is likely to be happy with the salary the company can offer, but also at whether the person has received raises when changing jobs. She also notes that employers can verify this information, so it's critical to tell the truth.

In the end, Phillips says, it's not usually a problem to give the employer the information. If bonuses or stock options were part of your pay package, mention this when you give salary numbers -- it could make a case for paying you more. If you know the position you're interviewing for pays less than you're making and you're OK with that, say so.

And remember that when the company actually makes an offer, you can still negotiate.