CMS Publishes 2021 Supplemental Security Income Ratios

The Centers for Medicare and Medicaid Services (CMS) published the Supplemental Security Income (SSI) percentages for fiscal year (FY) 2021.

Important information about the publication of percentages follows.

Key Information

Applicable Health Care Entities

CMS published SSI data for the following health care entities:

  • Inpatient Prospective Payment System (IPPS) hospitals
  • Inpatient rehabilitation facilities (IRFs)
  • Long-term care hospitals (LTCHs) that bill Medicare Administrative Contractors (MACs) for Medicare beneficiaries’ services


The FY 2021 SSI percentages can be accessed electronically on the CMS website, and the following pages focus on each applicable health care entity:

CMS also released a corresponding MLN Connects Newsletter Message on March 30, 2023.


On February 23, 2023, CMS issued Change Request 13101 (CR), providing technical direction to MACs.

The CR states that Medicare Part A “contractors shall update their IPPS, IRF, and LTCH provider specific files prospectively, within 30 days of the implementation date of this CR, using the latest year’s SSI Ratio posted to the CMS website as of the implementation date of this CR, except when explicitly directed otherwise by CMS.”

The guidance takes effect March 24, 2023.


The SSI data files contain:

  • Provider number
  • Provider name
  • Total SSI days
  • Total days
  • Total SSI ratio—the ratio of days for patients entitled to Medicare Part A attributable to SSI recipients

Methodology for Calculating FY 2021 SSI Ratios

Subsequent to the decision in Empire Health Foundation v. Azar, the methodology for calculating FY 2021 SSI ratios uses total Medicare days, consistent with CMS’ prior regulation.

Considerations for Hospitals

Hospitals should keep a few factors in mind based on their classification.

IPPS Hospitals

FY 2021 SSI ratios will generally apply to Medicare cost reports beginning on or after October 1, 2020, and prior to October 1, 2021, for settlement purposes.

For IPPS hospitals, this updated data will be used to determine their Medicare Disproportionate Share (DSH) adjustment.


IRFs will incorporate the updated percentages into their low-income patient (LIP) adjustment.


LTCH discharges paid under the short-stay outlier payment adjustment will use updated SSI data.

Benefit of an SSI Percentage Recalculation for IPPS Hospitals

Current CMS regulations allow a hospital to request a recalculation of its Medicare fraction or SSI ratio based on the hospital’s cost-reporting period if it’s different from the federal fiscal year—October 1 through September 30.

Hospitals should research annually whether their facility could benefit from an SSI percentage recalculation, also known as an SSI realignment or redetermination.

If this hasn’t been historically or consistently reviewed, it’s recommended that hospitals perform a look back through all years of their SSI data. SSI recalculations can provide additional opportunities to help increase your Medicare Disproportionate Share (DSH) reimbursement.

Properly analyzing your SSI data, however, can be a complex process. If appropriate patient level SSI data isn’t fully obtained and analyzed properly, a recalculation could decrease your Medicare DSH reimbursement.

Learn more about how to determine the benefit of an SSI percentage recalculation and what data and analysis is required, or request a complimentary analysis to determine if your organization could benefit.

We’re Here to Help

If you have questions about potential implications of the FY 2021 SSI ratios for your hospital or would like assistance evaluating whether your hospital would benefit from a recalculation, contact your Moss Adams professional.

You can also learn more about our Provider Reimbursement Enterprise Services and find related information.

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