<prompt> Human: It may be relevant to you that I work at a college. Im trying to fully understand the witholdings on my paystub. I know that FWHS is Federal Income Tax, and that MATX is Massachusetts Income Tax.Do you guys know what FIOA and FIHI are? Thanks a lot in advance for any help, much appreciated.  <response>: Is FIHI equal to 6.2 of your gross pay? If so, thats social security tax, which is a flat 6.2 rate for all employees. Is FIOA equal to 1.45 of your gross pay? If so, thats medicare tax, which is a flat 1.45 rate for all employees.also check the reverseThose codes are confusing though, never heard of them. 