99231
Subseq hosp inpt/obs sf 25 min
Subsequent hospital inpatient or observation care, per day, low-level medical decision making or 25 minutes of total time. CMS 2026 wRVU 0.76. Lowest of the three subsequent-care codes; used when the patient is stable and the day's work is observation only.
When to use it
Use 99231 for a stable inpatient day with minimal new decision-making: routine progress check, awaiting test results, low-acuity observation, awaiting discharge placement.
Full guidance
Examples: stable post-op day 2 on a routine pathway, day 3 of antibiotic course on stable trajectory, waiting for cardiology consult recommendation.
Documentation checklist
- ✓MDM low complexity OR 25 minutes total time on the date of the encounter.
- ✓Document the day's clinical status, ongoing plan, and any decision points.
- ✓Even on low-acuity days, capture the clinical trajectory and decision rationale.
Common pitfalls
- !Up-coding to 99232 when MDM is genuinely low. CMS audits the 99231-to-99232 ratio.
- !Time-based 99231 with no qualifying activities documented. List your activities (review labs, talk to family, write orders, document).
Payer notes
Medicare and commercial payers pay 99231 at the standard PFS allowable. Use this code conservatively; routine post-op days and observation-only days are the typical use case.