When's the best time to negotiate a severance package? Believe it or not, it's when you get hired.

Having provisions spelled out up front in case of a layoff is a negotiation tool that upper-level executives often use. But even if you're not a corner-office hire, there's no reason that you can't ask for a few assurances if worse comes to worst.

When you get a formal job offer, ask for an agreement to be included, such as three months' severance pay. Should you lose your job, you'll have your contract or offer letter with specific guarantees and possibly legal rights in hand. (Just remember where you filed the sucker.)

If you're already working and have been taking advantage of the Employee of the Month parking spot, then there's usually not much wiggle room on negotiating a better deal -- especially in a mass layoff situation. Most companies consult with a pack of lawyers to make sure the fateful day goes smoothly. Although they aren't too fearful of lawsuits, they are concerned about bad press -- both their outside reputation and among remaining employees.

Still, there are some measures you can take to soften the layoff blow. Here are a few tips we got from our resident Human Resources Fool:

Get everything you've been promised in writing. Remember, you cannot be forced to sign something on the spot. Take the paperwork with you, and agree to drop it off after you've had time to review it with a cool head. Consult a lawyer if need be -- especially if a lot of money is on the line or if you were axed before a bonus, commission, vesting period, or some other important deadline. Then schedule a time to come back with questions and show off your new golf swing. If you are dismissed "with cause," however, your former employer may not owe you a cent.

If you have some notice before the day the ax finally falls, do a little research. Call friends who have been through it -- in this economy, chances are a few of your pals can commiserate -- and compare severance-package notes. If nothing else, misery loves company.

Volunteer to stay for another 30 or 60 days. If you can set your emotions aside, offer to help with the transition, shut down your department, or train your remaining coworkers. By prolonging full pay and benefits, you can push off your severance for a little while. Besides, leaving on good terms is a good move. You'll benefit from a glowing reference and the satisfaction of being a bigger person than most.

Consult the employee manual. If you're determined to walk out the door with one of your employer's valuables, take the employee manual. You can glean some important info about policies, procedures, and the amount of time you can hang on to that sweet dental coverage.