[AnthonyMouse]

The >40% is of households. Children typically don't have their own households. And retirees can still pay income tax, both because social security is taxable and because they're making withdrawals from tax-deferred retirement accounts. It's not at all uncommon for higher income retirees to pay more income tax than lower income working people (as it should be, but the point stands that the retirees don't explain the total).