There is no set per diem. If you mean the rate paid for short stays:
Short stay outliers are defined as those patients with a length of stay between 8 days and two thirds of the arithmetic average length of stay (ALOS) for each LTC-DRG. These cases will be paid the least of: 150% of the LTC-DRG specific per diem payment, 150% of the cost of the case, or the full LTC-DRG payment.
I've been out of LTAC case mgmt for a few years but I believe the avg daily rate would work out to be closer to 1300/ day or about 39K / per admission. Payment is based on dx, length of stay,and geograhical location + outliers. Each DRG has a weight with an expected LOS, if the pt stays 5/6 of that LOS the LTAC gets the full DRG payment. IMHO: The games this creates along with the patient/family population you have to work with makes LTAC case mgmt is as challenging a position as you can find.