The tax department has raised service tax demand of about Rs 10,000 crore from information technology and IT-enabled services companies in the country, sending a shock wave through an industry already reeling under tighter US immigration laws and increasing automation.In its notices sent to about 200 companies so far, the service tax department has told them to return export benefits claimed in the last five years (2012-2016) on software provided to clients outside India, and has additionally sought 15% service tax along with fines, according to people in the know.