The ICD-10-CM code for gastric reflux (GERD) without esophagitis is K21.9; GERD with esophagitis is K21.00 (without bleeding) or K21.01 (with bleeding), because K21.0 itself is no longer billable.
Gastric reflux, acid reflux and gastroesophageal reflux disease all index to category K21, Gastro-esophageal reflux disease. The choice inside K21 turns on one question: did the provider document esophagitis? If not, the code is K21.9. If so, you need a sixth character that says whether there was bleeding.
Around the K21 codes sit several look-alikes that are easy to pick by mistake: Barrett’s esophagus (K22.7-), esophagitis from causes other than reflux (K20.-), newborn reflux (P78.83) and heartburn as a symptom (R12). This guide explains when each one applies, with official FY2027 titles (the code set in effect since October 1, 2026), a worked endoscopy example and the Official Guidelines rules behind each choice.
Key Takeaways
- K21.9 (GERD without esophagitis) is the default reflux code when no esophagitis is documented. Esophageal reflux NOS is indexed here.
- K21.0 has been a non-billable subcategory since October 1, 2020 (FY2021). Use K21.00 or K21.01 instead.
- Reflux esophagitis belongs in K21.0-, not in K20; K20 is for eosinophilic and other non-reflux esophagitis.
- Barrett’s esophagus is coded separately with K22.70 or a K22.71- code for dysplasia, alongside the K21 code when GERD is also documented.
- Reflux in a newborn is P78.83, which K21 excludes; R12 (heartburn) is for the symptom when no diagnosis has been made.
The K21 Codes at a Glance
| Code | Official title | Billable? |
|---|---|---|
| K21 | Gastro-esophageal reflux disease | No, category header |
| K21.0 | Gastro-esophageal reflux disease with esophagitis | No, subcategory header since FY2021 |
| K21.00 | Gastro-esophageal reflux disease with esophagitis, without bleeding | Yes |
| K21.01 | Gastro-esophageal reflux disease with esophagitis, with bleeding | Yes |
| K21.9 | Gastro-esophageal reflux disease without esophagitis | Yes |
Before October 1, 2020, K21.0 was a complete, billable code. The FY2021 update split it into K21.00 and K21.01, so any charge master, superbill, EHR favorite list or problem list still carrying K21.0 will produce claims with an invalid code (see how to keep a superbill template current). The same split happened in category K20 for other and unspecified esophagitis.
Do not submit K21.0 on any claim with a date of service on or after October 1, 2020. Clean it out of templates and pick lists, because a non-billable code is rejected before the payer ever reviews medical necessity. Our guide to CPT, ICD-10 and HCPCS code sets explains why truncated codes fail claim edits.
When to Use Each Gastric Reflux Code
K21.9. The provider documents GERD, acid reflux or gastric reflux and does not document esophagitis. This is the right code for most office visits, including patients managed on a proton pump inhibitor without endoscopy.
K21.00. The provider documents reflux esophagitis (for example erosive esophagitis seen at endoscopy) and no bleeding.
K21.01. The provider documents reflux esophagitis with bleeding, such as oozing erosions found during an EGD for anemia or hematemesis.
ICD-10-CM does not require a scope report for any of these codes. You code what the provider documents. Esophagitis is usually confirmed endoscopically, so in practice K21.00 and K21.01 tend to follow an EGD, but the code comes from the provider’s diagnostic statement, not from the procedure itself. If a payer policy asks for endoscopic findings to support a service, that is a coverage rule, not a coding rule.
Gastric Reflux vs Similar Codes
| Code | Official title | Use it when |
|---|---|---|
| K21.9 | Gastro-esophageal reflux disease without esophagitis | GERD with no esophagitis documented |
| K21.00 / K21.01 | GERD with esophagitis, without / with bleeding | Reflux esophagitis documented |
| K20.0 | Eosinophilic esophagitis | EoE diagnosed, usually on biopsy |
| K20.80 / K20.81 | Other esophagitis without / with bleeding | Specified non-reflux esophagitis, such as pill-induced |
| K20.90 / K20.91 | Esophagitis, unspecified without / with bleeding | Esophagitis with no cause stated |
| K22.70 | Barrett’s esophagus without dysplasia | Barrett’s on pathology, no dysplasia |
| K22.710 | Barrett’s esophagus with low grade dysplasia | Low grade dysplasia documented |
| K22.711 | Barrett’s esophagus with high grade dysplasia | High grade dysplasia documented |
| K22.719 | Barrett’s esophagus with dysplasia, unspecified | Dysplasia present, grade not stated |
| K22.10 | Ulcer of esophagus without bleeding | Esophageal ulcer documented |
| K22.2 | Esophageal obstruction | Stricture or narrowing of the esophagus |
| K44.9 | Diaphragmatic hernia without obstruction or gangrene | Hiatal hernia documented with the reflux |
| P78.83 | Newborn esophageal reflux | Reflux in a newborn (see below) |
| R12 | Heartburn | Symptom only, no reflux diagnosis made |
| R10.13 | Epigastric pain | Epigastric pain without a diagnosis |
| K30 | Functional dyspepsia | Provider diagnoses functional dyspepsia |
| R13.10 | Dysphagia, unspecified | Swallowing difficulty, phase not specified |
Reflux Esophagitis vs K20 Esophagitis
When the provider links esophagitis to reflux, the Alphabetic Index sends you to K21.0-, so the GERD code already captures the esophagitis. K20 codes are for esophagitis that is not due to reflux, or whose cause is not stated. Eosinophilic esophagitis (K20.0) is a separate disease and can be reported with K21.9 when both are documented.
For drug-induced esophagitis, follow the adverse effect rule in guideline I.C.19.e: code the nature of the adverse effect first (for example K20.80), followed by the T36 to T50 code for the drug with a fifth or sixth character of 5. Listing the T-code first reverses the guideline. The same sequencing applies to opioid-induced constipation, as our constipation ICD-10 code guide shows.
Barrett’s Esophagus With GERD
Barrett’s esophagus is classified separately in K22.7-, and the dysplasia status decides the code. When the provider documents both GERD and Barrett’s, report both. Sequence the condition chiefly responsible for the encounter first: a Barrett’s surveillance EGD usually lists the K22.7- code first, while a visit focused on reflux symptoms lists the K21 code first.
Newborn and Infant Reflux: P78.83
The K21 category carries an Excludes1 note for newborn esophageal reflux (P78.83), so the two are never reported together. American Academy of Pediatrics coding guidance applies P78.83 to infants 28 days old or younger, and to older infants whose reflux began within the first 28 days; once assigned, it stays in use for the duration of that condition. Reflux that starts after the newborn period is coded in K21. Neonatal and pediatric practices can see how we apply these rules on our neonatology billing and pediatric billing pages.
Heartburn (R12) and Other Symptom Codes
R12 is a symptom code. Use it when the provider records heartburn but has not diagnosed GERD, for example at a first visit before a trial of therapy. Once GERD is diagnosed, the guidelines say signs and symptoms routinely associated with the disease are not coded separately, so R12 drops off. Non-cardiac chest pain that the provider attributes to reflux is coded as K21, not as a chest pain R07 code.
In an outpatient setting, never code GERD from a rule-out or probable statement. Section IV of the Official Guidelines tells you to code the condition to the highest degree of certainty, which may be the symptom (R12, R10.13 or R13.10) until the provider confirms the diagnosis.
ICD-9 to ICD-10: What Changed for Reflux
ICD-10-CM replaced ICD-9-CM for dates of service on or after October 1, 2015. Under ICD-9, reflux without esophagitis was 530.81 and reflux esophagitis was 530.11. Those map to K21.9 and K21.0 respectively, and K21.0 was later expanded into K21.00 and K21.01. ICD-9 also made no distinction between infant and newborn reflux; P78.83 was new in ICD-10-CM.
| ICD-9-CM | Meaning | ICD-10-CM today |
|---|---|---|
| 530.81 | Esophageal reflux | K21.9 (or P78.83 for a newborn) |
| 530.11 | Reflux esophagitis | K21.00 or K21.01 |
Worked Example: EGD for Chronic Heartburn
A 58-year-old with years of heartburn has an EGD with biopsy. The report shows erosive esophagitis with no bleeding and a small hiatal hernia; pathology shows Barrett’s esophagus without dysplasia.
| Item | Code | Reason |
|---|---|---|
| Procedure | CPT 43239 | EGD with biopsy, single or multiple |
| Diagnosis 1 | K21.00 | Reflux esophagitis, no bleeding |
| Diagnosis 2 | K22.70 | Barrett’s esophagus without dysplasia |
| Diagnosis 3 | K44.9 | Hiatal hernia documented |
| Not coded | R12 | Heartburn is integral to the confirmed GERD |
If the claim is coded before pathology returns, Barrett’s cannot be reported yet; many practices hold endoscopy claims until pathology is final for exactly this reason. See our CPT 43239 billing guide for the procedure side.
Common Reflux Coding Errors and How to Prevent Them
- Billing truncated K21.0 instead of K21.00 or K21.01.
- Coding K21.9 when the report documents esophagitis, which understates the diagnosis.
- Reporting K20.9- for esophagitis the provider has linked to reflux.
- Adding R12 next to a confirmed GERD diagnosis.
- Using K21.9 for a newborn instead of P78.83.
- Coding Barrett’s from the endoscopy impression before pathology confirms it, when the impression is only suspected.
A diagnosis that does not support the procedure is a common cause of CO-11 denials on endoscopy claims.
- Read the final diagnosis. Look for esophagitis, bleeding, Barrett’s and dysplasia grade in the provider note and pathology.
- Choose the K21 code. K21.9 if no esophagitis, K21.00 or K21.01 if esophagitis is documented.
- Add separate conditions. Barrett’s (K22.7-), hiatal hernia (K44.9), stricture (K22.2) or EoE (K20.0) when documented.
- Drop integral symptoms. Remove R12 and similar symptom codes once a diagnosis is made.
- Check age. Use P78.83 for newborn-onset reflux.
Endoscopy claims live or die on diagnosis specificity. Steady Medical Billing’s gastroenterology billing team codes every EGD from the final report and pathology, so your reflux claims go out clean.
Frequently Asked Questions
What is the ICD-10 code for gastric reflux?
K21.9, Gastro-esophageal reflux disease without esophagitis, when no esophagitis is documented. If the provider documents reflux esophagitis, use K21.00 without bleeding or K21.01 with bleeding.
Is K21.0 a billable code?
No. Since October 1, 2020, K21.0 has been a subcategory header. Claims must use K21.00 or K21.01.
Does K21.00 pay more than K21.9?
Not by itself. Professional payment is set by the CPT or HCPCS service, not the diagnosis code. The diagnosis supports medical necessity and must match the documentation; choosing a code to raise payment is not compliant.
What is the ICD-10 code for reflux in a newborn?
P78.83, Newborn esophageal reflux. K21 excludes it, so do not report K21.9 for the same condition. AAP guidance applies P78.83 when reflux begins within the first 28 days of life.
Can I code heartburn and GERD together?
Usually not. Heartburn (R12) is a symptom routinely associated with GERD, so once GERD is diagnosed, R12 is not coded separately. Use R12 alone when heartburn is documented without a confirmed diagnosis.
