Black taxpayers are disproportionately likely to be audited, according to a Stanford University report released in January. The research team found that Black taxpayers receive audit notices at least three times more often than non-Black taxpayers.

Depending on their income, household size and filing status, they may be as much as 4.7 times more likely to be audited.

Stanford law professor Daniel Ho, who led the research, said the disparity likely isn’t intentional but the result of cost-cutting measures and the secret algorithm governing the IRS’ audit selection methods.