US · guidance
CMS Pub. 100-02, ch. 4, § 30
Reduction for Psychiatric Services in General Hospitals
A3-3104.4, HO-217.4
When an individual subject to a reduction in days is an inpatient in a general hospital the
A/B MAC (A) will apply the reduction only if it has determined that the individual was
an inpatient primarily for the diagnosis or treatment of mental illness.
The A/B MAC (A) normally will make a decision based on the principle diagnosis shown
on the claim. The reduction will not be applied where the principle diagnosis is not
related to mental illness, even though other diagnoses may relate to mental illness.
If the A/B MAC (A) needs more information than the principle diagnosis to make the
required determination, it should obtain it from the hospital, the attending physician, or
other appropriate source. Any case in which a reasonable question persists about whether
the individual was an inpatient "primarily for the diagnosis or treatment of mental illness"
should be resolved in favor of not applying the reduction.
The term “mental illness” is defined as the specific psychiatric conditions described in
the “American Psychiatric Association's Diagnostic and Statistical Manual - Mental
Disorders.”
History
(Rev. 1, 10-01-03)
Provenance
- Source
- cms.gov
- Retrieved
- 2026-08-25
- Edition
- iom-2026-08-25
- Content hash
c86007fd6675c9c0c11f6f1c4c9f443b257683b194e81496738c28970d4885b7
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