20 Miss. Code R. § 2-II
The IRF must possess a Medicare/Medicaid provider number, or CMS Certification Number. The provider number consists of six digits. The first two digits indicate the state, 25 is for Mississippi, and the remaining four digits identify the facility as an IRF. The four digit suffix must be in the range of 3025-3099 for rehabilitation facilities, exempt units must have a T in the third position, e.g., 25TXXX.
Unless governed by contract between payer and provider, or unless total billed charges are less, the reimbursement for an IRF under this Fee Schedule shall be the IRF PPS calculated rate multiplied by 1.8. Other inpatient MS-DRG or PPS calculations are not appropriate to use for IRF services. The IRF PPS rate is calculated using the formula for the current fiscal year, including outlier. The final calculation is published in the Federal Register, prior to October 1 of each year.
IRF reimbursement is based upon the case mix group (CMG) to which the patient is assignedand the CMG assigned by the Medicare CMG grouper. The CMG must be reported on the claim with revenue code 0024. This code indicates that this claim is being paid under the PPS and the revenue code can appear on a claim only once.
The Federal Register explains the formula for calculating the IRF PPS rate. The rates are calculated on CMG assignment from the combinations of ICD-10-CM codes with additional factors of labor share, wage index, rural adjustment (if applicable) and low income percentage (LIP) for a final adjusted IRF PPS reimbursement.
This calculated IRF PPS reimbursement is multiplied by 1.8 to determine the reimbursement rate.
Reimbursement rates are based on the date of discharge, using the Medicare Pricer for the appropriate year, which is available as a free download from : http://www.cms.hhs.gov/PCPricer [File Link Not Available]. The Medicare pricer returns the payment rate specific to the facility.
20 Miss. Code. R. § 2-II