It is usually pleasant to find some extra money hidden under the mattress. So the claim that China has at least Rmb10,000bn ($1,470bn) in “grey” or undeclared income might be good news – more wealth for the government to tax and perhaps a bit more potential spending from Chinese consumers. Yet dismay should be the Politburo’s principal response to the findings of a recent study by the National Economic Research Institute, a

non-governmental group.

The study, sponsored by Credit Suisse, is based on more than 4,000 anonymous interviews in 64 cities around the country. It provides a cross-check to the official quarterly income reports from the National Bureau of Statistics. When asked by the authorities, households seem routinely to understate their wealth out of fear that the taxman will get the data. Incomes according to Neri are on average 90 per cent higher than the NBS version. The gap was 78 per cent three years ago.