“…Finally, a third branch in the literature is concerned with tax rate harmonization when governments can levy differentiated taxes under either the origin or the destination principle. If competition in the goods market is perfect, and the government faces no revenue constraint, then an approximation of tax rates leads to aggregate welfare gains, as it improves exchange efficiency under the destination principle (Keen, 1987(Keen, , 1989 and production efficiency under the origin principle (Lopez-Garcia, 1996). The conditions for tax harmonization to constitute a Pareto improvement become much more stringent, however, when tax revenues are needed to finance a public good (Delipalla, 1997;Lockwood, 1997;Lahiri and Raimondos-Møller, 1998;Lopez-Garcia, 1998).…”