From what I have seen, the payroll and tax functions are outsourced to specialist firms. They do validate whether the document is correct for the IT exemption, you are claiming. I don't know if they validate the genuineness of the documents but I am aware of a case where an employee, who got thrown out, when it was found that fake medical bills were submitted. This was from the time when they used to allow 15k tax exemption for medical bills.