CPT 99231: Subsequent Hospital Care, Straightforward or Low Decision Making
99231 reports a follow-up visit to a hospital inpatient or observation patient when the decision making is straightforward or low, or when total time on the date reaches 25 minutes.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: 99231 is the entry level for daily hospital rounding. Medicare pays one hospital visit per patient per day to a physician or same-specialty group, and surgeons seldom get paid for it during the global period of their own procedure.
What Does CPT 99231 Report?
99231 is a follow-up E/M visit for a patient who is already in the hospital as an inpatient or in observation. Since January 1, 2023, one set of codes covers both settings.
The CY 2026 fee schedule final rule prints the descriptor. In plain words: a daily follow-up visit with a medically appropriate history or exam and straightforward or low MDM, or at least 25 minutes of total time on the date when time picks the level.
| Item | Value in the file |
|---|---|
| Short label CMS uses | Sbsq hosp ip/obs sf/low 25 |
| Payment status | A (active code) |
| Work RVU | 1.00 |
| Facility total RVU | 1.32 |
| Global period | XXX (the global concept does not apply) |
| Non-facility setting | Marked NA: rarely or never done there |
A work RVU is the physician work part of the payment weight.
When Should You Use 99231, and When Not?
The level follows either decision making or total time, not the length of the note. 99231 fits the day when the decision making is straightforward or low.
MLN006764 says it would not be medically necessary or appropriate to bill a higher level of E/M service when a lower level is more appropriate. When time selects the level you must provide the full time, and the CPT midpoint rule does not apply, so 24 minutes does not round up to 25.
- If time selects the level, write the total minutes or a start and stop time, as MLN006764 asks.
- Do not use 99231 for the first visit your group makes during the stay. Section 30.6.9 E of Chapter 12 calls that an initial service, and it belongs to 99221 to 99223.
- Do not use it for a discharge visit by the attending physician. That is 99238 or 99239.
A practitioner who is not the attending physician but managed other problems reports a final inpatient visit with 99231 to 99233, not a discharge code (Chapter 12, section 30.6.9.2 B).
How Does the One-Visit-per-Day Rule Treat 99231?
Chapter 12, section 30.6.9 B, says the MAC pays a physician for only one hospital visit per day for the same patient, whether the problems seen are related or not.
If physician A rounds in the morning and physician B, covering for A, sees the patient in the evening, section 30.6.9 C says the second visit is not paid. The exception is different specialties handling different aspects of care with different diagnoses. In that case both visits are paid.
A hospitalist sees a patient at 9 a.m. and a partner in the same group checks a lab at 6 p.m. The day carries one code for the combined work. Billing 99231 twice invites a duplicate denial.
Can a Surgeon Bill 99231 During the Global Period?
Usually not for the stay in which the surgery happened. Section 30.6.6 A of Chapter 12 says the contractor does not pay inpatient hospital care furnished during the hospital stay of the surgery, because all care in that stay is paid through the global surgical payment. The exception is a visit for another medical condition that is unrelated to the surgery.
When the visit is unrelated, the claim carries modifier 24 and the note must show why the problem is not part of postoperative care.
How Does 99231 Appear on the Claim?
On the CMS-1500, Item 24D carries 99231 with its modifiers and Item 24G carries 1 unit. Item 24E points to the diagnosis in Item 21 that supports the visit. Item 24B takes the place of service: Chapter 26 says to use 21 for a registered inpatient, 22 for an on-campus outpatient and 19 for an off-campus outpatient.
Modifier AI is for the initial hospital care code, not for 99231. A visit shared by a physician and a nurse practitioner follows the split or shared visit rules.
Which Item 21 and 24E Fields Support 99231?
Chapter 26 says Item 24E takes one diagnosis reference from Item 21 per line, a letter from A to L on the 02/12 form. The daily visit line should point to the diagnosis that explains why the patient is still in hospital that day.
What Payment Edits Apply to 99231?
The NCCI practitioner services MUE table effective October 1, 2026 lists 99231 with a value of 1 and adjudication indicator 3, a date of service edit based on clinical rationale. That means one unit per date of service.
Chapter XI of the 2026 NCCI Medicare Policy Manual says a subsequent per diem code is not reported with an initial per diem code on the same date.
Why Is 99231 Denied?
| Code | What X12 says | What usually causes it |
|---|---|---|
| OA-18 | Exact duplicate claim or service | Two members of one group billed 99231 for the same patient and date |
| CO-97 | The benefit is included in the payment for another service already adjudicated | A surgeon's routine postoperative visit inside the global package, or a second visit the same day |
| CO-151 | The payer deems the information does not support this many or this frequency of services | More than one unit, or repeated daily visits flagged without notes that show a change |
| CO-4 | The procedure code is inconsistent with the modifier used | A modifier such as 24 on a visit that the payer reads as postoperative care |
If these denials keep coming back, our denial management team can work them. The higher levels are 99232 and 99233.
Related Codes
- Medicare Claims Processing Manual, Chapter 12: Physicians/Nonphysician Practitioners · CMS
- Medicare Claims Processing Manual, Chapter 26: Completing and Processing Form CMS-1500 Data Set · CMS
- Physician Fee Schedule relative value files, RVU26D (October 2026) · CMS
- Medicare NCCI Medically Unlikely Edits, practitioner services table, effective 10-01-2026 · CMS
- Evaluation and Management Services (MLN006764, May 2026) · CMS
- 2026 NCCI Medicare Policy Manual, Chapter XI: Medicine and Evaluation and Management Services · CMS
- CY 2026 Physician Fee Schedule final rule (90 FR 49266) · Federal Register
- CY 2023 Physician Fee Schedule final rule (87 FR 69404) · Federal Register
- Claim Adjustment Reason Codes · X12
- Place of service code set · CMS
We check every rule, code and deadline against the official source. See our editorial policy.
Common Questions
Straight answers from the team that does the work.
Ask a billing lead directly. A 20-minute call, Monday to Friday, 9am to 5pm Eastern.
01What is CPT 99231?
It is the lowest of three follow-up hospital visit codes for inpatient or observation patients: straightforward or low decision making, or 25 minutes of total time on the date when time sets the level, per the CY 2026 fee schedule rule.
02How many minutes do you need for 99231?
When you pick the level by time, 25 minutes of total time on the date must be met or exceeded, per the CY 2026 final rule. MLN006764 says the CPT midpoint rule does not apply, so a 24 minute day does not qualify. You can also pick the level by decision making instead.
03Can two doctors in the same group bill 99231 on the same day?
Not for the same specialty. Chapter 12 section 30.6.9 says the contractor pays one hospital visit per patient per day. A covering physician in the same group is not paid for a second visit. Different specialties with different diagnoses can both be paid.
04Does 99231 need modifier AI?
No. Chapter 12 says the principal physician of record adds modifier AI to the initial hospital care code, 99221 to 99223. Follow-up visits in the facility are billed as subsequent hospital care, and the AI modifier does not go on them.
05Can I bill 99231 for observation patients?
Yes. Since 2023 inpatient and observation care use the same codes; the old observation codes 99224 to 99226 were deleted. The treating practitioner bills 99231 to 99233, and others who see the patient in observation bill outpatient codes, per MLN006764.
Rounding Claims Coming Back?
We code each day from the note and work the denials that follow.