How payment works — two separate money streams

One ICU stay generates two independent bills that never come out of each other. Confusing them is the most common error.

CPT / E&M codes generate your professional dollars (total RVU × conversion factor, adjusted by local GPCI; CY2026 non-APM CF $33.40, QP/APM CF $33.57). ICD-10 diagnosis codes add no professional RVUs — they establish medical necessity and drive the facility MS-DRG and its severity tier (CC/MCC). FY2026 national standardized operating base rate $6,752.61, before wage index/DSH/IME/outliers.

DRGs come in tiers — with MCC (highest) / with CC / without CC-MCC. The tier is set by the single highest-severity secondary diagnosis: one MCC maxes the tier, so the first MCC/CC captured is the valuable one. Capturing a CC is typically worth ~$1,200–$3,000; an MCC ~$3,000–$6,000+.

Color key: MCC major (highest $) CC complication/comorbidity Neither no severity weight Procedure drives DRG via procedure code

Common questions

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Critical Care E/M — 99291 & 99292

Critical care is time-based, not complexity-based. Both must be true: (1) a critical illness/injury acutely impairing a vital organ system with high probability of imminent life-threatening deterioration, AND (2) high-complexity physician work directing care to treat/prevent it. ICU location alone, or a sick-but-stable patient, does not qualify.

Time → code mapping

Medicare requires the full additional 30 minutes before the first 99292 (74 + 30 = 104 min). Some commercial payers allow partial increments.

Capturing time across multiple attendings (and APPs)

Document total critical care minutes in every note and let coding assign 99291/99292 — physicians should not self-select the codes. That one habit captures the most and prevents the common miss of billing 99291 but forgetting 99292.

• Same group + same specialty aggregates. Two PCCM attendings in the same group are treated as one physician — their minutes on the same patient/same calendar day combine. The group reports 99291 once for the first 30–74 min, then 99292 for each additional 30. Example: 20 min + 85 min = 105 min → 99291 + 99292.
• They cannot each bill 99291 (double-billing) — the time combines into one group claim. A different-specialty physician does bill a separate 99291.
• Aggregation works even if neither attending reached 30 minutes alone — the combined time qualifies.
• Each provider's time must independently be critical care, and simultaneous bedside time is counted once, not doubled.
• With APPs in the group, same approach — both names & minutes in the notes; coding applies the FS modifier and split/shared logic (see Residents & APPs).

What time counts (and what doesn't)

• Counts: bedside time AND unit/floor time on that patient — reviewing labs/imaging, discussing with consultants/staff, documenting, and family discussions when the patient can't participate and the discussion drives management.
• Doesn't: separately billable procedure time (carve it out), teaching time, time off the unit, time on other patients.

Bundled into 99291/99292 — never billed separately

Anything NOT on this list (intubation, CPR, central/arterial lines, chest tube, thora/paracentesis, LP, cardioversion, bronchoscopy, pacemaker, Swan-Ganz) is separately billable — but its minutes must be carved out of critical care time.

Billing with residents & APPs (academic settings)

Who may bill and whose time counts depends on whether you're with a resident (Teaching Physician rules) or an APP/NPP (Split/Shared rules). Don't conflate them.

Residents — Teaching Physician (TP) rules

• Only the teaching physician's own time counts. Resident-alone time and teaching time don't count toward critical care minutes.
• A resident can't bill critical care, and there's no split/shared with a resident. The service is billed under the TP.
• The TP personally furnishes the billed critical care time and documents their own minutes + management. May refer to/combine the resident's note for history, exam, and assessment, but writes their own attestation and time statement.
• Append modifier GC when a resident participated.
• The primary-care exception / GE modifier does NOT apply to critical care.

APPs / NPPs — Split (or Shared) Visit rules

• Applies when a physician AND an APP (NP/PA) in the same group both personally perform part of the same patient's care on the same calendar day in a facility setting. (Incident-to does not apply to hospital inpatient/ICU care.)
• Critical care: sum the physician's and APP's minutes; whoever performed the substantive portion (>50% of combined time) bills. For time-based services, substantive portion = time only, not MDM.
• Append modifier FS to any split/shared visit, regardless of who bills.
• Document both individuals by name, each one's time, the combined total, and who did the substantive portion; the billing practitioner signs/dates.
• Payment lever: APP-billed pays ~85% of the fee schedule; physician-billed (substantive portion) pays 100%.

Quick decision guide

Medicare rules; commercial payers may differ. Split/shared substantive-portion definitions have shifted year to year — confirm current CMS/MAC policy.

Critical care RVUs & reimbursement

Worked example: 2 h 10 min (130 min) = 99291 + 99292×2 = 4.50 + (2.25×2) = 9.00 wRVU ≈ $399. The same day billed as 99233 = 2.00 wRVU ≈ $98 — roughly a 4× difference for documenting time correctly.

National, unadjusted facility RVUs × $33.40. Local payment varies with GPCI.

Procedure billing

Most ICU procedures are separately payable in addition to same-day critical care, but: (1) attach the right modifier so the payer doesn't bundle them into the E&M, and (2) carve the procedure time out of critical care minutes.

CY2026 Medicare PFS, national/unadjusted, total facility RVU × $33.40. Verify against the CMS PFS Look-Up Tool before billing.

Necessary elements of a billable procedure note

• Indication / medical necessity — why now.
• Informed consent (or documented emergency exception).
• Time-out / patient ID for invasive procedures.
• Technique & site — approach, laterality, anesthesia/prep, image guidance (and whether guidance is bundled).
• Findings, specimens, devices placed (size, depth, confirmation — e.g., CXR for line position).
• Complications (or explicit “none”) and post-procedure status.
• Provider attestation + supervision/teaching-physician statement if a trainee assisted.
• Time statement confirming procedure time was excluded from critical care minutes.

Modifiers that matter in the ICU

Most ICU bedside procedures carry a 000-day global, so same-day critical care with -25 is generally payable. Check NCCI edits for the specific pair.

Procedures that drive the DRG — ICD-10-PCS

ICD-10-PCS is the facility procedure code set on the hospital claim — separate from the CPT codes you bill professionally. Every code is 7 characters, each an independent axis: section, body system, operation, body part, approach, device/duration, qualifier. The coder builds it only from your documentation and can't infer a missing axis — so what you write decides which code lands.

Worked example 1 — mechanical ventilation

5A1955Z — invasive ventilation, >96 hours

Character 5 alone moves the money — the 96-hour cliff (respiratory dx, base rate $6,752.61):

Counted as continuous hours from intubation to extubation — so the note needs times, not “on the vent for days.” BiPAP/NIPPV is a different code and does not count toward these hours.

Worked example 2 — CRRT

5A1D90Z — renal replacement, continuous (>18 hrs/day)

Here the procedure barely moves the DRG — the lever is the diagnosis it treats:

For CRRT, capture two things: the continuous modality (character 5 = continuous vs 5A1D70Z intermittent), and the acute kidney failure / ATN it’s treating — the diagnosis is what bumps the tier, not the filter.

The other ICU procedures, ranked by DRG leverage

How to write the note so it’s captured

• Timestamps over adjectives. Every vent/ECMO/CRRT duration code is computed from documented start/stop times.
• Name the modality. Continuous CRRT vs intermittent HD; invasive vent vs BiPAP; VA vs VV ECMO.
• Link the procedure to its diagnosis. CRRT only earns its keep when the acute kidney failure (N17, a CC) is documented and coded.
• New procedure vs chronic status. A trach placed this stay drives 003/004; “chronically trached at baseline” is a status code and does not.

Educational documentation-improvement reference. PCS-to-DRG assignment changes annually; verify codes against the current ICD-10-PCS tables, the FY2026 MS-DRG Definitions Manual, and AHA Coding Clinic.

Diagnoses by organ system

Top ICU diagnoses with confirmed CC/MCC status (CMS Appendix C, FY2026). Search and filter; the documentation tip is where specificity changes severity.

DRG value ranking — what each condition is worth

Actual FY2026 MS-DRG relative weights (CMS IPPS Final Rule, Table 5), highest value first. Edit the base rate to match your hospital; dollars recalculate live. Click a column header to sort.

National, unadjusted (before wage index, DSH/IME, transfer/outlier). Ventilation/trach DRGs (003/004/207/208) are procedure-driven — vent hours >96 vs ≤96 (207 vs 208) is the single biggest lever.

Complex care & long length-of-stay

The chronically critically ill: capture severity, present-on-admission (POA) status, and ventilation duration. Some conditions forfeit DRG credit if hospital-acquired (HAC).

Pressure injury stage 3/4/unstageable = MCC (HAC if not POA). Vent >96h (PCS 5A1955Z) vs ≤96h (5A1945Z) is the biggest single lever. CLABSI/CAUTI = HAC if not POA.

Decompensated cirrhosis

Cirrhosis itself is only a CC; the decompensations win the severity. Code cirrhosis PLUS each decompensation present.

AKI in cirrhosis: hepatorenal syndrome (K76.7, MCC) vs ATN/prerenal (N17, CC) — the distinction changes the tier. Note: hepatic encephalopathy K76.82 is not a CC/MCC; capture hepatic failure with/without coma (K72.x) for severity.

Malnutrition

Severe = MCC; moderate/mild = CC. Requires physician documentation tied to ASPEN/GLIM criteria — an RDN note alone is not enough. BMI (Z68.x) does not establish malnutrition.

Note must contain: physician diagnosis + severity, etiology, criteria met (intake, weight loss %, muscle/fat loss, fluid, grip), intervention, and follow-up. Severe malnutrition (MCC) is often worth ~$3,000–$6,000+ on a stay with no other MCC.

Chronic trach-to-vent patients

Status codes don't drive the DRG. The procedure (ventilation hours) and acute respiratory failure move payment.

“Chronically vented at baseline” = chronic respiratory failure (CC). A new acute change (hypercapnia, pneumonia, failure to wean with decompensation) = acute-on-chronic respiratory failure (MCC) — document the acute change explicitly.

Sources & caveats

• Diagnosis CC/MCC status confirmed directly against the CMS ICD-10 MS-DRG v43 (FY2026) Definitions Manual, Appendix C Part 1 (the list underlying IPPS Tables 6I/6J). Status can change annually.
• DRG relative weights from the CMS FY2026 IPPS Final Rule (CMS-1833-F) Table 5; national standardized operating base rate $6,752.61.
• Professional RVU/$ figures use CY2026 Medicare PFS values (conversion factor $33.40); national, unadjusted. Confirm individual codes against the CMS PFS Look-Up Tool before billing.
• Teaching physician and split/shared rules per the CMS Medicare Claims Processing Manual / MLN and ACEP FAQs; substantive-portion definitions have shifted year to year.
• Caution: icd10data.com shows DRG groupings, not a code's own secondary-dx CC/MCC status — a common source of error. Statuses here were read from Appendix C itself.
• This is an educational documentation-improvement reference — not coding, legal, or financial advice, and not an official CMS, AMA, or MGMA product. CPT® is a registered trademark of the AMA. Final code assignment rests with certified coders/CDI and your compliance team.

Built as a static reference site. Values current as of the FY2026 / CY2026 Medicare rules. Re-verify at the next ICD-10 / MS-DRG / PFS update.