Withdrawals from the 457 plan are allowed after you retire, separate from service, die, or become disabled. Withdrawals may also be made for "unforeseeable emergencies" - a severe financial hardship resulting from a sudden and unexpected illness or accident to a plan participant or dependent.*
When you withdraw funds from your 457 plan, you will pay current income taxes on it - unless you roll the sum into another tax-deferred vehicle.
* It is very difficult to qualify for an emergency withdrawal. To do so, you must satisfy strict IRS rules. For more information, or to obtain the proper forms to request an emergency withdrawal, contact your plan service provider.