This paper applies recently developed time series and heterogeneous panel nonlinear unit root tests to 24 OECD and 33 non-OECD countries’ consumption-income ratios over the period 1951–2003. This extends evidence provided in the recent literature to consider nonlinear adjustment in time series and panel unit root tests, and substantially expands both time series and cross sectional dimensions of data analysed. We find that there is nonlinear reversion to a mean or trend for just over half of OECD countries and just under half of non-OECD countries.