I recently added my partner to my employer's benefits, and because we're not married the employer's cost for his benefits is (very unfortunately) added as imputed income to my income for tax purposes.
I'm trying to calculate how much extra this is going to cost in taxes (in addition to the payroll deduction for my portion of the cost of the plan itself). Any ideas re: the simplest/best way to do this accurately?
For federal taxes, should I be multiplying the additional imputed income by my marginal rate or effective rate? I was thinking marginal, since this new imputed income is incremental, so it's taxed at my top bracket rate, right?
I assume it's possible that my bracket might even go up due to this imputed income?
Does the same logic hold for state and local taxes (NY and NYC)?