Hong Kong ( CNN ) -- China 's urban rich are making far more than they officially report , suggesting the wealth gap in the world 's second largest economy is much higher than previously thought , according to a new study . The China Society of Economic Reform released a survey Monday that found `` gray income '' was 6.2 trillion yuan ( U.S. $ 1 trillion ) , or 12 % of GDP . `` Gray income '' can range from illegal cash from kickbacks to unreported income and gifts . `` The result has highlighted expanding social inequalities and policy issues surrounding official corruption and income distribution , '' said Wang Xiaolu , who led the research for the CSER , in an article in Caixin Online . `` The richer the household , the more likely it receives shadow income . '' The study comes a day after Bo Xilai , a once high-flying politician , was sentenced to life in prison for bribe-taking,15 years for embezzlement and seven years for abuse of power . Bo is appealing the verdict . The CSER surveyed 5,344 urban families in 18 Chinese provinces . The results suggest the top 10 % of households earn nearly 21 times more than the poorest 10 % . The National Bureau of Statistics places income disparity far lower , saying China 's wealthiest make 8.6 times more than its poorest . `` China is in a dangerous zone as one the most unequal countries in the world , '' Wang wrote . The survey found that rich families gain 80 % of their wealth from business and on average `` have decent gains '' in stock markets , whereas most middle and lower income families lose cash in the capital markets , Wang said . `` We ca n't rule out that some of these business gains are problematic , or even illegal , because many survey takers count kickbacks as business gains , '' he wrote . Much of the high gray income is linked to the loose credit handed out between 2009 and 2010 , Wang wrote , as well as the rapid increase of government investment during the same period . `` To stop widening income disparity and unfair allocation , in addition to anti-corruption campaigns , there needs to be gradual but firm progress in economic , political and social reform that moves the country closer to the rule of law with public scrutiny over administrative power , '' he said .
Survey : China 's urban rich are making far more than they officially report . Researchers found unreported `` gray income '' was $ 1 trillion ( China 6.2 trillion yuan ) Suggests the top 12 % of households earn 18 times more than the poorest . `` The richer the household , the more likely it receives shadow income ''