The fixed price in the AWS Reserved Instance Asset report may not match the total expected full term upfront cost for the reservation if the reservation has been modified.  In this case the displayed fixed price will be prorated based on the updated purchase date and expiration date. 

As an example, if the difference between the purchase date and expiration date on a three year reservation with a full up front cost of $1,997.00 is 396 days and 3 hours left, the displayed fixed price will be calculated as:

(modified RI duration)/(initial RI duration) * (up front cost) = fixed price

((396 + 3/24) / (365 * 3)) * 1997 = 722.4307