FORTUNE -- Dear Annie: I applied for an opening as a senior marketing manager at a Fortune 500 company two months ago and have since been back for three rounds of interviews. The meetings have gone really well, but they haven't made an offer yet.
I just had a meeting with the person who'd be my immediate boss, plus a human resources person, and they asked me, "What are your salary requirements?" I have only a hazy idea of what pay range they have in mind, and we haven't discussed benefits at all, so -- caught off guard -- I added 10% to what I made in my last job and told them that number. Was that the right way to handle it? If not, what should I have said instead? --Second Thoughts
Dear S.T.: Ah! No surprise that you were caught off guard. You've been hit with the dreaded so-called "pre-offer." Gary Bergmann, a senior consultant at Boston-based outplacement and executive coaching firm ClearRock, says he has been seeing more and more pre-offers in recent months.
"This is a way for employers to feel out someone they want and get an idea what salary it will take to land that person, without having to make a formal offer first," he says. "They're telling you they want to make only one written offer they know you will accept."
The bright side is that they apparently want your talented self. The tricky part, as you've noticed, is that they've put you on the spot and made you play a guessing game.
"The rest of the compensation package -- including medical, dental, vacations, bonuses, 401(k) contributions, stock options if any, and so on -- can easily have an impact on what salary range would be acceptable to you," Bergmann notes. "It's not likely you can make a sound business decision if you have only a small part of the information you need."
Hence his advice to his coaching clients who get pre-offers: "If you receive a pre-offer, you should pre-negotiate." How? The ideal way to answer the question would have gone something like this: "My base salary requirements are flexible depending on the rest of the compensation package. Given that my qualifications are an excellent fit for this job, I believe a fair salary range would be between $X and $Y, again depending on the rest of the package. Is that within the range you have in mind?"
This approach "gets the right conversation started and quickly indicates that you need to know more than just the potential base salary," says Bergmann. "Once they provide you with all the facts, you can have a more balanced discussion."
Talkback: Have you ever gotten a "pre-offer"? How did you handle it? Leave your comments at the bottom of this story.
Okay, so they blindsided you, and you had to think fast. You'll be better prepared next time, but it's still not too late to remedy this situation. "Remember that the best time to negotiate is after an offer has been made and before you have accepted it," says Bergmann. "Once the offer is made, the balance of power shifts from the one making the offer to the one considering it, so be prepared to use this leverage to your full advantage."
In practical terms, this means that, if the company has still not made you a formal offer, you have to get busy and figure out the fair market value of the job you're up for. Bergmann recommends checking out pay ranges for comparable jobs on Web sites like Salary.com, JobNob.com, and GlassDoor.com, as well as asking recruiters (if you know any), and seeking out salary survey data from trade associations.
Then, when and if a formal offer comes your way (with information about benefits included), compare it with what you've learned about compensation in similar jobs. Take your time. "Don't reject a low offer on its face without asking why it's below fair market value," Bergmann advises.
On the other hand, don't be too quick to jump at a big salary, "even if it's beyond your expectations," he says. If the offer is way out of line with what similar jobs pay elsewhere, there is probably a reason for that too. Try, tactfully, to find out what it is. If, for example, the last 5 people hired for this job quit within a year because the boss is an unbearable tyrant, you're better off knowing that now than discovering it later.
Let's say the company takes you at your word and makes you an offer based on the figure you already gave them -- and you find out, through your research, that it is on the low side. Or let's say the salary is okay, but the benefits turn out to be skimpy.
"Always ask permission to negotiate," Bergmann suggests: "Instead of diving right into the heat of battle with 'I feel I deserve a higher salary because of my credentials,' for instance. A stronger opening would be, 'With regard to the salary (or vacation time or whatever the sticking point is), I'd like to know if you have any flexibility with that.' If the answer is 'no,' move on to the next point. If the reply is, 'What did you have in mind?' you've been given the green light."
One more tip from Bergmann: "Use the word 'need' rather than 'want' when you negotiate, to underscore what it will take for you to accept the job." Good luck.
Talkback: Have you ever gotten a "pre-offer"? How did you handle it? What are the best secrets for negotiating salary? Tell us on Facebook, below.