ZKJ specializes in taxation laws of Pakistan, as in many jurisdictions, a tax can be levied only by, or under, the authority of an Act of Parliament. While taxation of income (other than agricultural income) is governed by the Income Tax Ordinance 2001 as amended from time to time, the Sales Tax Act 1990 deals with sales tax at Federal level. Tax law, body of rules under which a public authority has a claim on taxpayers, requiring them to transfer to the authority part of their income or property. The power to impose taxes is generally recognized as a right of governments. … The development of tax law as a comprehensive, general system is a recent phenomenon.