Tax planning is increasingly being regarded not as a legal issue but a moral one, with campaigners treating tax as part of the wider debate on “corporate social responsibility.” This article looks at the modern tax debate in the light of Christian theology and biblical teaching, first as to how to vote on tax issues and second how to react to existing tax law. It suggests two basic principles for a theology of taxation: 1. Our charitable duty to our neighbor is personal and cannot be satisfied through the taxation system. There is therefore no general Christian duty to vote for tax-funded welfare. 2. Our Christian obligation toward taxes is to obey the law, as interpreted by those who have been put in authority to do so; there can therefore be no category of legal but immoral tax evasion.