Difference Between Outpatient Coding and Inpatient Coding (With Table)

Hospital is an institution serving patients in huge numbers daily. Serving to the number of patients and maintaining their record is a must.

Patients requirements and the way he’s diagnosed can be broadly divided into two categories, inpatient and outpatient.

Systematic documentation of the patient belonging to any category between two becomes necessary while billing and coding. There are people employed for this challenging task

The patient’s initial condition before admitting, the diagnosis, and the outcome of the diagnosis hugely varies concerning the patients need and depending on which it’s divided into Outpatient and Inpatient coding.

For the person seeking a career in the medical field and even, it becomes important to understand the difference and opt for a preference at the first. A workplace works differently as per profession and the job one is employed at so the differences help to have an early stage training and development of skills.

Outpatient Coding vs Inpatient Coding

The main difference between Outpatient Coding and Inpatient Coding is the time period a patient stays in the hospital. Outpatient coding is specifically done for patients who are not admitted for a longer time and get departure within 24 hours whereas under the prescription of a doctor the patients admitted for more days are generally handled by the inpatient coders carrying a detailed diagnostic report.


Comparison Table Between Outpatient Coding and Inpatient Coding

Parameters of Comparison

Outpatient Coding

Inpatient Coding

Time of stay

Such coding is done specifically for those patients who just come for a checkup and don’t stay for more than a day in the hospital.

The coding is designed concerning the patients to stay, the patient staying for more than 24 hours falls under it.


Outpatient Prospective Payment System (OPPS) provides reimbursement to their respective patients.

The Inpatient Prospective Payment System (IPPS) is the method for the inpatients in accordance with their diagnosis, it’s reimbursement plan by the government and the healthcare providers.

Coding System

ICD-10-CM and HCPCS Level II codes are designed to report the details and documentation.

ICD-10-PCS and ICD-10-CM are used to report all the essential data associated with the patient’s stay.


The illness is often not established and defined, in that case, the patient most of the time revisits for further checkup.

The diagnosis is well defined and the requirements and cost can be predefined.


Outpatient coding is easier and less complex

Inpatient coding goes through the complexity of data arrangement and documentation for as long as the patient is hospitalized.


What is Outpatient Coding?

Outpatient coding is a kind of medical coding used by the hospital to document the procedures performed and the requirements for the outpatients. it’s detailed reporting.

Outpatients are the people who come to seek direct treatment usually taking a few hours and technically within 24 hours.

The stay of outpatients in the medical facility is less, so is the complexity in the coding, but the same outpatient might frequently re-visit.

The coders seeking a job for outpatient coding require certain qualifications and it’s necessary to have proper knowledge of coding, the most commonly used coding are ICD-10-CM and HCPCS Level II.

It lacks a defined diagnosis that the coding of uncertain diseases is strictly prohibited, the coders can, however, signs and symbols can be used.


What is Inpatient Coding?

Inpatientcoding is the coding system in any medical facility where the detailed analysis and process of diagnosis are listed and documented precisely to ease the overall visit of a patient and of the hospital itself.

Inpatients are those people who are admitted for a longer stay, they are hospitalized for as per the requirements of diagnosis. To classify a person as an inpatient the stay should be more than 24 hours, lasting to furthermore days.

Inpatient coding requires the coder to be pro in both ICD-10-PCS and ICD-10-CM coding systems. They are the basis of the qualification criteria.

The process can be complicated and complex depending upon the stay as prescribed by the doctor. All the facilities like food, medicines, and their data are registered.

Inpatient can claim a reimbursement under Medicare Part A, The Inpatient Prospective Payment System (IPPS) helps in managing and regulating policies.

Main Differences Between Outpatient Coding and Inpatient Coding

  1. The main difference between Outpatient Coding and Inpatient Coding is based on the number of days and times a patient is admitted for. The outpatient coding is for the patients not staying for more than 24 hours while the stay of inpatients is longer as the patients are formally asked to get hospitalized.
  2. The outpatient coding of a single patient can reoccur as the diagnosis is not well defined in the first visit and one can be asked to visit in weeks, whereas the inpatient coding generally ends after the discharge and proper diagnosis
  3. The complexity of outpatient coding is comparatively less than that in inpatient coding as inpatients start longer and their every requirement and facilities provided are well documented.
  4. The Outpatient coding requires the coders to have the knowledge of codes and guidelines of ICD-10-CM and HCPCS Level II whereas an inpatient coder should be pro in ICD-10-PCS and ICD-10-CM.
  5. OPPS (Outpatient Prospective Payment System) is a system managing the reimbursement for outpatients, for inpatients the Inpatient Prospective Payment System (IPPS) seeks reimbursement.



Hospitals are an institution of noble people providing healthcare to the vulnerable, they include the doctors, surgeons, nurses, and staff. Each person has a certain essential job to carry out and facilitate the whole process.

Among them are the coders, the outpatient coders, and inpatient coders dealing with every patient visiting for treatment and documenting every step and requirements, they also regulate the reimbursement from medicare

The outpatient coding strictly codes for the patients visiting and leaving within 24 hours, it’s less complex and utilizes the knowledge of codes and guidelines of ICD-10-CM and HCPCS codes.

Inpatient coding is a complex set of documents documenting a patient’s visit and stay for more than 24 hours. It utilizes ICD-10-PCS and ICD-10-CM.coding.


  1. https://academic.oup.com/ajhp/article-abstract/60/suppl_6/S11/5143321
  2. https://onlinelibrary.wiley.com/doi/abs/10.1002/mpr.1559