When valuing retirement benefits are there tax consequences?

When benefits are distributed by the plan to the employee, taxes will be assessed just as they are against a regular pay check. Therefore, it makes sense that taxes should be examined when valuing future retirement benefits. However, how much tax is appropriate and at what tax rate? Since the answers to these questions are presently unknown, most appraisers and courts, alike, are wary of applying a reduction to the value for future taxes.