Zakat satisfies the four famous principles of a fair taxation system as set up by Adam Smith: fairness, certainty, simplicity, and convenience. Smith considered these four pillars as the backbone of a just system of redistribution of wealth. In his attempt to sustain his argument that Zakat is an Islamic system of redistribution which parallels with the Western idea of taxation, Siddiqi provides that in regards to fairness, Zakat is levied on the individual’s savings for the period of twelve months, therefore, people with bigger savings will contribute more. As an effect, the poorer people of the community will not be prejudiced, as people with no savings are not obliged to pay Zakat. Taxes, on the other hand, are levied on the income of individuals and increase proportionally as there is an increase in income, leading relatively to more sacrifice being made by the poor than the rich, as no account is taken of the amount of wealth accumulated by the individual. Furthermore, it is the poor who benefit more from the revenues of Zakat, which helps to serve one of its main objectives: to provide social justice. Siddiqi adds that Zakat provides certainty for the payer, with its fixed rate of 2.5% of an individual’s wealth. He supports this argument by referring to the fact that the rate, objective, and beneficiaries of Zakat are immutable, unalterable, and based on its divine sanction. He adds that in regards to time, amount of payment, and forms of expenditure, both for the contributors and the governments, no man-made tax can offer more certainty than Zakat does. In terms of convenience, Siddiqi argues that Zakat is also convenient because it is paid annually and by those who are able to pay it, i.e., those with wealth exceeding Nisab. Also, Zakat offers the convenience of paying it according to its manner of production (i.e., land produce, cattle, articles of trade, or in cash). Finally, when it comes to simplicity of calculation, Zakat is a fixed and understandable rate, therefore making its collection costs lower than other tax systems.
Ref - AlMatar, F., 2015. Zakat vs taxation: the issue of social justice and redistribution of wealth. European Journal of Business, Economics and Accountancy, 3(3), pp.119-129.