If you are referring to imputed income as it relates to group life insurance, you can find a calculator for that factor at this website: http://www.aetna.com/individuals-families-health-insurance/plans-benefits/life/imputed-calc.html.
That will tell you what part of the group life insurance policy you will be taxed on.
That will tell you what part of the group life insurance policy you will be taxed on.