Once you've decided to move from one company to another and completed the slog of your job search, what do you do when your boss offers a raise to keep you? The conventional wisdom says you should always summarily decline counteroffers, but does that really apply to every situation? In a word, No. Approaching counteroffers is a tricky thing, but sometimes--just sometimes--staying put with a better package can make a lot of sense. But be warned: When you do that, you've put yourself on dangerous ground.

Your Days Are Numbered

Although on the surface getting a counteroffer is flattering, a different reality may lurk beneath the surface. "Your manager may panic and offer you more money while he searches for your replacement," notes Joe Kotlinski, partner and manager of IT Search at WinterWyman, a Boston staffing firm. "As soon as he finds someone to take your place, you become expendable." It’s true that managers usually shore up their bench once the cat is out of the bag. At the same time it’s difficult to replace a top performer with exceptional technical skills, so if you don’t burn a bridge your job may be secure for the foreseeable future. The keys to your security are your performance, stature and how your manager's handled similar situations in the past. Still, don't kid yourself. You're reputation isn't going to be what it once was. If your company has historically replaced defectors or eliminated highly paid employees when business lags, keep your resume handy. When it comes to letting people go, your name's going to be at the top of the list.

Your Increase Will Be Temporary

"Salary is only one part of total compensation, and things tend to even out over time," says Mike Wondrasch, a vice president at Valley Forge, Pa., staffing firm AmeriSourceBergen. "You may get smaller increases or bonuses in the future, especially if your raise wasn't based on merit or the attainment of new technical skills." Even if they've offered you more money, companies that tend to underpay don't change on a whim. If your new salary is near the top of the scale or exceeds what others are making, you could face a cut after your manager plans for your departure, which he'll probably do whether you stay or not. Be sure your counteroffer includes a genuine raise, not some sort of temporary bonus, and always base your decision on the whole picture, since we all know that salary and compensation packages rise and fall.

You’ll End Up Leaving Anyway

Although recruiters insist that 80 to 90 percent of employees who accept counteroffers depart within a year, that turnover is usually due to unresolved issues like a cultural mismatch or a lack of chemistry with your superiors. In those cases, there's no reason to stay given the uncertainty of your future. On the other hand, it could be worth remaining in place if you genuinely like the company and your resignation results in a real promotion or a chance to learn new skills.

Your Relationship With Your Boss Will Be Damaged

If your boss is one of those who takes things personally or carries a grudge, you may never be able to mend the fence. If you've had an open relationship and he's treated others well under similar circumstances, you may be able to carry on without fear of reprisal. Indeed, a manager who's really paying attention to the dynamics of his team may have seen your move coming. Your resignation could give him the argument he needs to get you a better package. It's rare, but it happens. Still, occasionally a great opportunity will arise just when someone is about to leave, observes WinterWyman's Kotlinksi. For instance, your boss could be moving on and has recommended you for a promotion or a high-visibility project. If your decision to leave stemmed from a lack of growth or opportunities, it may make sense for you to hang around.