If the 457 plan is the only one your employer offers, the limits are the same as with a 401(k) - a maximum of $18,000 in 2016 for those under 50 years old, and up to $24,000 for those 50 and over.
But here's the difference: If your employer also offers a 401(k) or 403(b) plan, you can contribute to both the 457 and the other plan. Moreover, you can invest up to the maximum in each account. In 2016, the limits are $18,000 in each type of account, plus catch-up contributions - so you could make a total retirement contribution of as much as $36,000 (or $48,000 if you are 50 or older). Investing the max in both is a terrific option if you're getting started saving a little late, or you just want to maximize the advantages of these plans (tax breaks and matching, if any).
Even if you’re not eligible for another plan, special 457(b) has additional catch up provisions in for workers three years from the retirement age (as specified by their plan) to stash an additional $36,000 if you haven’t maxed out your retirement savings in previous years.