Optimal tax in his article titled "Using Elasticities to Derive Optimal Income Tax Rates" derives a formula for optimal level of income tax using the both compensated and uncompensated elasticities. Saez writes the tradeoff between equity and efficiency is a central consideration of optimal taxation, and implementing a progressive tax allows the government to reallocate their resources where they are needed most. However, this deters those of higher income levels to work at their optimal level. Saez decomposes the marginal effects of a tax change into mechanical, behavioural and welfare effects, as follows: The sum of these effects should be zero at
From each according to his ability, to each according to his needs can be found in the Guilford Covenant in 1639: Some scholars trace the origin of the phrase to the New Testament. In Acts of the Apostles the lifestyle of the community of believers in Jerusalem is described as communal (without individual possession), and uses the phrase ""distribution was made unto every man according as he had need"" (): However, other scholars disagree with this, and claim that the phrase 'from each according to their abilities, to each according to their needs' has a non-religious origin, in 'the Roman legal concept of obligation in solidum' The Roman legal concept of obligation