Zakat is a tax on wealth, not income, which makes it structurally unlike almost every modern charitable norm: it falls on what has been sitting for a year, at 2.5%, and it deliberately erodes hoards. The Quran fixes eight categories of recipient — the poor, the needy, those who administer it, those whose hearts are to be reconciled, captives, debtors, those in God's cause, and travelers — and classical Islamic states collected and distributed it as public finance. Voluntary giving beyond it has its own name, sadaqa.