momtax n., The bite of my sons' sandwiches/candy bars/ice cream/whatever to which I am automatically and eternally entitled by virtue of the cooking, cleaning, monitoring and general support services I perform daily, not to mention the four hours of labor per child, ten and four years ago respectively.*
*yes, I know that constitutes an easy labor. If yours was worse, you may levy a correspondingly higher tax. Two bites, perhaps, or even three.