Supporters partly relied for justification on a 2004 FAIR study that estimated that Arizona taxpayers were annually paying $1 billion to cover the education, uncompensated health care, and incarceration costs of illegal immigration, net of the taxes paid by the illegal immigrants. This study appeared to contradict a 2003 study performed by a team at the Thunderbird School of Global Management and sponsored by Wells Fargo and the Consul General of Mexico in Phoenix, which estimated that immigrants were annually contributing $318 million more in income and sales taxes than they were costing the state in services and uncompensated health care. However, it was not clear whether that estimate was based on all immigrants or only illegal immigrants.