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  • Writer's pictureSpencer Dunlap

Capital Deep Dive: X12 Transaction Sets

Updated: Jan 7, 2022

Our previous article covered the 837P and 837I transaction sets for claims along with their origins through ANSI, X12, and HIPAA, so what about the others? We have put together all of the information here so you have everything you need to become an expert on healthcare transaction sets.

Let's start with a breakdown before describing each - you'll notice our 837s and 835s in here, too:

​X12 ID

Transaction Set

Official Name



Additional Information to Support a Health Care Claim or Encounter



Health Care Claim Status Request and Response



Health Care Claim Request for Additional Information



Health Care Claim Acknowledgement



Health Care Eligibility/Benefit Inquiry and Information Response



Health Care Claim: Professional



Health Care Claim: Institutional



Health Care Claim: Dental



Health Care Claim Payment/Advice

X12 ID: This is X12's own identifier for each transaction set. X12 breaks these out since it's possible for one transaction set to serve multiple purposes (e.g., multiple variations of 837 and 277).

Transaction Set: The code for the data content exchanged for specific business purposes. These are defined by a numeric identifier and name.

Official Name: How X12 defines each transaction set.

Transaction Set Descriptions


The 275 transaction set provides additional patient information, typically serving the same purpose as a Claim Attachment. Attachments are needed when payers require the submission of additional detail with the claim, such as a Certificate of Medical Necessity for certain sleep studies. This file format is currently extremely uncommon (about 20% adoption as of 2019), with providers generally mailing paper claim attachments or transferring common file types - like PDFs - to the payer instead.


The 276 transaction set is a claim status request. Use of a 276 would take place after a provider has already submitted the 837 and is looking for a status update on what's happening with their claim, such as whether or not it was successfully processed, adjudicated, or held up for some reason. Some EHRs and billing systems can automatically generate and send 276s, freeing up the time of insurance follow-up staff otherwise spent on the phone with payers. After sending a 276, the provider would be expecting a 277 back.

Claim status request and response transaction sets


The 277 transaction set is the response to the 276 status request and provides information on a claim status such as whether or not it was processed, adjudicated, or if it was rejected or denied. The 277 can either be solicited or unsolicited, simply meaning it's either in response to the provider's 276, or sent just as part of the payer's process, respectfully. The 277 can serve more than one purpose, sometimes being used as a simple response to a 276, while some payers may use the 277 to request additional information of the provider.


The 270 transaction set is similar to the 276 in the sense that it's a request to the payer for information, but this time to check for a patient's eligibility with their insurance. This generally happens very quickly, garnishing the term "Real-Time Eligibility", which you may have heard before. This is a key part of the patient registration process, as failing to check a patient's eligibility is a common cause of claim denials.


The 271 transaction set is simply the payer's response of eligibility to the 270 query. Unlike the 277, you would not expect to see a 271 unsolicited.

In the bottom four rows of the table you can see the claim and remittance transaction sets that we covered previously, but here's a quick re-cap:


The 837 transaction set is the claim form itself that the provider bills to the payer. This transaction set contains the provider, patient, patient visit, and any other information the payer requires to adjudicate. There are multiple types of the 837 depending on the need.

837P: For Professional Billing, an electronic claim is called an 837p (“p” for professional), and the paper claim form is referred to as a CMS-1500.

837I: For Hospital Billing, an electronic claim is called an 837i ("i" for "institutional"), and the paper claim form is referred to as a UB-04.

837D: For Dental Billing, an electronic claim is called an 837D ("d" for "dental").


The 835 transaction set - remittance/payment advice - is the payer's response to a claim (837) that the provider sent out previously. This file contains various codes that indicate levels of payments or responses to each of the charges on the respective 837, which we will be covering more in-depth in a Capital Deep Dive focused solely on remittance.

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