The price of some tax bases (energy and carbon) are traded on open marketplaces and the prices are thus relatively transparent (Liu, 2013). If at least a portion of carbon-energy tax revenue is used to reduce conventional taxes, or if revenue is recycled to individuals (through improved welfare systems) or to businesses paying conventional taxes, then this may reduce incentives for firms and individuals to join or stay in the informal sector, as the gap between the tax burden in the formal and informal sector is reduced (Fay et al., While carbon-energy taxes apply equally to all energy users, whether in the formal or informal sector, conventional taxes on wages, sales and profits apply only to the formal sector.