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.