The prototypical model would be a lump sum X, unconditionally granted to every adult citizen/resident on a regular basis, regardless of income. Tax rates are k

The prototypical model would be a lump sum X, unconditionally granted to every adult citizen/resident on a regular basis, regardless of income. Tax rates are kind of a perpendicular issue. If you view benefit phase-outs as a kind of implicit tax rate, this would make the tax code flatter (and more progressive, if you're counting benefit phase outs as a kind of implicit tax).