The aim of this paper is to explain differences among OECD countries i
n the evolution of taxes on labour during the last two decades. Its ma
in message is that these taxes are to an important extent structurally
and institutionally determined. Tax rates on labour are shown to have
risen more strongly in countries where: (i) government has been contr
olled mainly by leftist parties; (ii) taxes (in general) are decided a
nd collected mainly by central government (fiscal centralization); (ii
i) coalition and minority governments are frequent; (iv) the partisan
composition (political colour) of these coalitions is unstable; (v) th
e labour market is neither centralized nor decentralized.