Rollovers are only permitted between qualified retirement accounts. Rollovers from nonqualified (nongovernmental) 457(b) plans are not permitted. The distribution from the nongovernmental 457(b) is taxable and the deposit into the governmental 457(b) is an excess contribution. The excess contribution must be corrected as such, otherwise the money will be taxed a second time when later distributed as an ordinary distribution from the new employer's 457(b).
Entering a negative amount of other income to offset the taxable income from the nongovernmental 457(b) plan would be improper. The rollover chart to which AmyC linked applies only to qualified retirement accounts (governmental plans in the case of a 457(b)).
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