The 3-day payment window: what Medicare bundles into the inpatient claim

What is the 3-day payment window?

The 3-day payment window puts a patient's preadmission outpatient services inside the inpatient payment. 42 CFR 412.2(c)(5) names "preadmission services otherwise payable under Medicare Part B furnished to a beneficiary on the date of the beneficiary's admission to the hospital and during the 3 calendar days immediately preceding" the admission as part of the inpatient operating costs that the IPPS payment covers.

Chapter 3, section 40.3 of the Medicare Claims Processing Manual is the billing instruction. It counts the admission date plus the three calendar days before it, so the window is four dates long. For a patient admitted on a Wednesday, the manual puts Sunday through Wednesday in the payment window.

Two conditions apply. The beneficiary must have Part A coverage, and the services must come from the admitting hospital, an entity it wholly owns or wholly operates, or another entity under arrangements with it.

Which hospitals does the window apply to?

It applies to IPPS hospitals and to hospitals and units excluded from the IPPS, but not to critical access hospitals. Acute care hospitals paid under the IPPS use three days. Excluded hospitals and units use one day.

The CAH carve-out trips up groups that own several facilities, because ownership by an acute care hospital changes the answer. Our critical access hospital billing page covers the CAH payment method.

What gets bundled and what can be billed separately?

Diagnostic services are always bundled. Nondiagnostic services are bundled unless the hospital attests that they are unrelated to the admission. The manual sorts every case this way.

The manual defines "diagnostic" by what is on the bill. Its revenue code list includes 030X laboratory, 032X diagnostic radiology, 035X CT scan, 040X other imaging, 073X EKG and 074X EEG. A revenue code such as 0300 for laboratory therefore points to bundling.

The emergency room line is different. Revenue code 0450 for the emergency room is not on the diagnostic list, so an ED visit that precedes an admission is a nondiagnostic service. It is deemed related to the admission, and the ED charges go on the inpatient claim unless the hospital attests otherwise.

How does the bundling show up on the claim?

The hospital puts the outpatient information on the inpatient claim. Section 40.3.D says it must include "the diagnoses, procedures, and charges for all preadmission outpatient diagnostic services and all preadmission outpatient nondiagnostic services" that meet the rule. It must convert the CPT codes to ICD-10-PCS procedure codes and include only services inside the window.

Those codes sit on the claim that is grouped to an MS-DRG. The present on admission indicator follows a special instruction: code any condition the patient had at the time of the order to admit as present on admission, even if the patient was registered as an outpatient when it was found.

The service that stays outpatient carries its own markers. An unrelated nondiagnostic outpatient claim needs condition code 51 in the condition code fields, form locators 18 to 28 of the UB-04 under chapter 25. Our UB-04 revenue and condition codes page covers those fields.

Section 40.3.B says the Common Working File (CWF), Medicare's claim history system, rejects diagnostic outpatient claims when the through date or last date of service (occurrence span code 72) falls on the admission day or in the three days before it. From July 1, 2008 it also checks the line item date of service.

How does modifier PD work for hospital-owned physician practices?

Modifier PD marks a physician practice service inside the window. The October 2026 HCPCS file lists it as "Diagnostic or related non diagnostic item or service provided in a wholly owned or operated entity to a patient who is admitted as an inpatient within 3 days," added January 1, 2012 with no termination date.

Section 90.7.1 of chapter 12 requires modifier PD on the physician preadmission diagnostic and related nondiagnostic services reported with HCPCS or CPT codes. It makes the hospital responsible for telling the practice about the inpatient admission. Medicare then pays only the professional component of codes with a professional and technical split, and the facility rate for codes without a split. Unrelated physician nondiagnostic services go without PD.

The practice must be wholly owned or wholly operated. 42 CFR 412.2 says a hospital wholly owns an entity when it is the sole owner, and wholly operates it when it has exclusive responsibility for the entity's routine operations, whether or not it sets policy. The facility versus professional billing guide explains the two claim types.

The window makes no change to global surgery billing, but when the surgery itself falls inside it, PD goes on the surgical code. See global surgery periods.

What does a window case look like?

What if a window service was billed separately?

The CWF edit rejects the bill in process, and the hospital has to reconcile both. Section 40.3.B says that hospitals "must analyze the two bills and report appropriate corrections." Section 40.3.1 adds that separately billed services included in a related admission are rejected as duplicates and can bring sanctions under section 1128A of the Social Security Act.

Read the remittance. X12 defines CARC 97 as a benefit included in the allowance for another service already adjudicated, and CARC 18 as an exact duplicate claim or service. Match the claim lines to the dates before you decide which applies.

1. Pull the outpatient and inpatient claims and list each outpatient service by date and by diagnostic or nondiagnostic type.
2. Add the bundled services, with their diagnoses, ICD-10-PCS procedure codes and charges, to the inpatient claim by an adjustment under chapter 3, section 50.
3. For an unrelated nondiagnostic service, rebill the outpatient claim with condition code 51 and keep the clinical documentation.
4. Check the filing clock: 42 CFR 424.44 requires a Medicare claim within 1 calendar year after the date of service.
5. If the MAC denied a claim as a duplicate in error, ask for a reopening. 42 CFR 405.980 treats duplicate denials as clerical errors, which a party can ask the contractor to reopen at any time.

For other errors, a party can request reopening within 1 year for any reason or within 4 years for good cause under 42 CFR 405.980(c). A redetermination must be requested within 120 calendar days of receiving the notice under 42 CFR 405.942(a), and the notice is presumed received 5 days after its date. The Medicare appeal levels page covers what follows.

If this rule is costing you claims, our denial management team can help, and the full scope is on hospital and facility billing.