You may hear the footsteps of an impending layoff months ahead of time, if you're lucky. The company may be offering buyouts, with the promise of layoffs if enough people don't take the money and run. Or your boss is reassigning some of your duties, or your company recently merged and someone else at the new company already does your job.
Whatever footsteps you hear, or even if you don't hear them, it's a good idea to get a layoff emergency kit together so that you're moving forward as quickly as possible after a layoff. Here are some things to "pack" now before you're called into the boss's office: