SAN FRANCISCO, Oct 15 (Reuters) - The head of California"s largest union was arrested on Friday, a day after the prominent activist was charged with grand theft and tax fraud. Alma Hernandez, the executive director of SEIU California, and her husband Jose Moscoso were charged on Thursday with allegedly underreporting some $1.4 million of income between the 2014 and 2018 tax years. Another complaint alleged that Hernandez, while working on a political action committee for a Democratic state senate candidate in 2014, approved a $11,700 payment to her husband for services he did not provide. Moscoso also allegedly did not disclose that his air duct-cleaning business had multiple employees, resulting in over $300,000 in unreported wages. SAN FRANCISCO, Oct 15 (Reuters) - The head of California"s largest union was arrested on Friday, a day after the prominent activist was charged with grand theft and tax fraud. Alma Hernandez, the executive director of SEIU California, and her husband Jose Moscoso were charged on Thursday with allegedly underreporting some $1.4 million of income between the 2014 and 2018 tax years. Another complaint alleged that Hernandez, while working on a political action committee for a Democratic state senate candidate in 2014, approved a $11,700 payment to her husband for services he did not provide. Moscoso also allegedly did not disclose that his air duct-cleaning business had multiple employees, resulting in over $300,000 in unreported wages. Hernandez was being held at The Sacramento County Main Jail and was ineligible for bail, according to the Sacramento County Sheriff"s Office"s website. SEIU California said that Hernandez, a 42-year old who had led the union for 11 years, had resigned. "We are deeply concerned about the allegations against Alma Hernandez," wrote Bob Schoonover, the president of SEIU California State Council, in a statement. "We have accepted Ms. Hernandez"s resignation, and we have cooperated fully with authorities on this matter and will continue to do so." Reuters was not immediately able to contact Hernandez, Moscoso, or their lawyers. Hernandez faces two counts of grand theft, one count of perjury and five counts of filing a false income tax return with intent to evade. The Sacramento County Sheriff"s Office"s website did not immediately list Moscoso as an inmate and a call requesting information went unanswered. The SEIU in California has over 700,000 members, who work in a broad range of fields and include social workers, janitors, and doctors.