CHILD-SUPPORT payments should be regarded as a statutory tax on fatherhood, and not a voluntary contribution, Baroness Hollis, the social security minister in the Lords, has announced. She said the Child Support Agency White Paer, due to be debated next week,would propose replacing the complex maintenance formula with a simple fixed-rate levy of 15 per cent of net income for one child, 20 per cent for two and 25 per cent for three or more.