Please help me understand this. You promise to pay someone $x,  but you will only pay $x-90%(say $y)<p>The person receiving $y is actually getting it from the very taxes they pay. So essentially what you are giving them is a tax discount. Except in cases where a person makes $0, for which you have social security anyway.<p>So this is basically a tax discount? You could simply say based on their income some a% of tax discount will be offered every year.