SEATTLE — Immigration and Customs Enforcement reached its highest number yet of companies audited for illegal immigrants on their payrolls this past fiscal year.

Audits of employer I-9 forms increased from 250 in fiscal 2007 to more than 3,000 in 2012. From fiscal 2009 to 2012, the total amount of fines grew to nearly $13 million, from $1 million. The number of company managers arrested has increased to 238, according to ­data provided by ICE.