Episode 3: Decoding the CMS 1500

What is the CMS 1500?

In this episode, Sage explains the CMS 1500 claim form, goes into detail on each box of the form, and gives tips on how listeners can enter this information into their EHR system successfully to avoid claim rejections. Listen now or check out the transcript below!


Hi there! Thank you for joining us for another episode of Billing Breakthroughs, a podcast devoted to helping you find billing success. My name is Sage, and I’m a Billing Specialist here at TheraNest.

Today we’ll be taking a deep dive into the CMS 1500 form so that we can demystify and draw connections between the elements of the form and the claims you submit through your practice management software.

Why CMS?

Strengthening your knowledge of the CMS 1500 form will help you to confidently enter information into your practice management software, submit claims for the services you render, and handle the clearinghouse rejections and insurance payer denials that come your way. As an added bonus, your understanding of the CMS 1500 form may even help in reducing the number of rejections and denials you receive because you’ll have nailed your information input on the first try!

CMS vs. EDI:

So I’ll start by going over the difference between the CMS 1500 form and the EDI .837 file.

EDI stands for Electronic Data Interchange. The EDI .837 is an electronic file used to transmit claim data between your EHR system, your clearinghouse, and the insurance payer. This type of file is a more recent creation that was born in conjunction with the advent of medical practice management software and the rise of electronic claim submission. Clearinghouses also sometimes call this form the 837P.

The CMS 1500 form, on the other hand, shows up much earlier on the timeline of medical claim submission history. Although it was developed by The Centers for Medicare and Medicaid (which is where the CMS acronym comes from), it’s become the standard form used by all insurance payers. If you were to print a paper claim and send it to an insurance payer, you would utilize the CMS 1500 form.

There are 33 fields on a CMS 1500 form which are called “boxes”. When using a practice management software like TheraNest, each box corresponds to a field of information that you have entered into your client demographics and appointment details. In other words, the information you enter into your EHR directly affects how the CMS 1500 forms for your claims will populate.

Importance of CMS 1500 with Electronic Claim Submission:

Okay, I know what you’re thinking: I submit my claims electronically, why should I care about the CMS 1500 form?

Well, here’s the thing: although the electronic claim submission process doesn’t use the CMS 1500 form to transmit the data of the claim, insurance payer denials are often communicated back to providers and billers in terms of the CMS 1500 form boxes.

For example, if you’ve spent some time billing electronically, you may have come across the denial reason code, “Rejected claim because no taxonomy is present.” Bewildered, you may have contacted the insurance payer and asked what the heck that denial code means, to which they likely responded something like, “The taxonomy code is required in box 33b.” If you don’t have much familiarity with the CMS 1500 form, this might have felt to you like a frustratingly unhelpful response.

My hope is that by us going over the boxes on the CMS 1500 form, you will be equipped to connect the dots between the information you enter into TheraNest and the claims that you submit.

CMS 1500 Form Boxes:

Alright, let’s get to it. To keep this from turning into an extremely long podcast, I’m going to keep my explanations of each box fairly simple and I’ll also note the location of each box’s corresponding information fields within the TheraNest system. If you’re looking for a print out version of this podcast that you can reference in the future, I encourage you to use the TheraNest Knowledge Base to find the CMS 1500 Claim Form Guide.

The first section of the CMS is the carrier block, which lives at the very top of the form. This field corresponds with the insurance name and address, which can be edited in TheraNest through the Insurer Details page.

Box 1 is simple, but vital: the Insured’s ID Number, which is the member ID you will find on your client’s insurance card. If this number is incorrect, your claim will most certainly be rejected or denied. You will enter in the Insured’s ID Number from the Bill To & Insurance Info tab of your Client Profile.

Boxes 2 and 3 are also found in the Client Profile in TheraNest, but on the Client Details tab. Box 2 populates the client name and Box 3 populates the client’s gender.

Box 4 is the Insured Name, meaning the primary insurance subscriber. In TheraNest, you can enter Information About Insured through the Bill To & Insurance Info tab. If you choose “Self”, this means the primary insurance subscriber is the client and the information for this box will be taken from the Client Details. If the primary subscriber is not the client, you will enter the information of the primary subscriber (which is usually a spouse or parent) in that Information About Insured section in the Bill To & Insurance Info tab.

Box 5 pulls the client address from the Client Details.

Boxes 6 and 7 both have to do with the primary subscriber, and they populate according to how you filled out the Information About Insured section of the Bill To & Insurance Info tab. Box 6 is the “Relationship to Insured” field, which is usually either self, parent, or spouse. Box 7 is the Insured’s Address: if your client is the primary subscriber and you chose “self” for relationship to insured, this address will be the same as Box 5.

Box 8 isn’t filled by TheraNest, so we aren’t going to worry about that one.

Box 9 indicates if the client has a secondary insurance policy. If the client does not have secondary insurance, this box is left blank.

Box 10 specifies if the condition treated by the service rendered is related to an auto accident, other accident, or employment. In the Bill To & Insurance Info tab you’ll find a dropdown menu asking if the client’s condition is related to an accident, with options No (the default), Employment, Auto Accident, or Other Accident. If anything other than No is selected, you will be prompted to enter a few more details related to the accident that will populate segments A through C of Box 10.

Box 11 is filled depending on the insurance type of the client’s insurer. Typically this box is filled by the Policy or FECA number (or the group number, if the former field is empty). Box 11a is filled by the insured person’s date of birth and gender, while box 11c is filled by the Insurance Plan Name. All these fields can be found under the Bill To & Insurance Info tab.

For Box 12, if the “Release Medical Records and Billing Info to Insurance” option in the Bill To & Insurance Tab is marked “Yes”, then the “Signature on File” value is used along with the date of the form creation. If the option is marked “Not Required”, then both fields are empty.

Boxes 14 through 16 are not filled by TheraNest.

Box 17 is related to the Referrer information input in the Bill To & Insurance Info Tab. The name and NPI of the referring provider must be entered in TheraNest in order for this box to populate, and the qualifier will show as “DN”.  If you have marked the “Use Supervising Provider on Claims” option as “Yes”, then the DQ qualifier will populate.

Boxes 18 through 20 are not filled by TheraNest.

Box 21 shows the diagnoses for services billed. Diagnosis codes are taken from the client’s Initial Assessment of the client case containing the progress note related to the service billed.

Box 22 is only populated if the claim you are submitting is a resubmission. In TheraNest, this will only populate if the EDI file settings for the insurance payer of this claim claim has the “Ask for resubmission details prior to re-submit failed claim” box checked. If you do not want this box to populate, you will need to go into the EDI file settings for this insurer and uncheck the “ask for resubmission” setting.

Box 23 is for a prior authorization number, if applicable. In TheraNest, prior authorization numbers can be added from the Bill To & Insurance Info tab.

Box 24 relates to the billed services of the claim, including the date of service, place of service (default is 11 – Office), CPT codes and modifiers, diagnosis pointer, charges, units of service, staff member (which is the rendering provider) and the ID qualifier (if applicable) such as provider taxonomy. If this insurance payer requires an ID qualifier, you can add this under the Additional Insurer ID field of the Insurer Details.

Box 25 is populated by the Billing Provider specified in the invoice. If the “Bill With Selected Staff NPI” box is checked in the invoice details, the Tax ID of the selected provider is used. Otherwise, the Organization Tax ID is used.

Box 26 is populated by the client ID. This is not to be confused with the Insurance ID, the client ID is an ID number or letter combination that either you can create or generate through the Client Details tab.

Box 27 is determined by whether or not the “Accept Assignment” – meaning that you are agreeing to accept the insurance payer’s approved amount as full payment for covered services. In TheraNest you’ll find this option under the Bill to & Insurance Info Tab, and as a default it is checked Yes. Generally, you should choose Yes for this option unless you are billing the claim as out of network.

Box 28 is just the sum of all charges and Box 29 is the sum of payments on the claim (if the claim had been previously submitted and paid by primary insurance).

Box 30 is not filled by TheraNest.

Box 31 is filled by the name of the Rendering Provider associated with the claim. If no staff is associated with the invoice in TheraNest, then the words “Signature on File” will populate this box.

Box 32 includes a myriad of things: Line 1 is the Facility Name, and Lines 2 and 3 are the location address. If the claim’s service item is connected to an appointment in TheraNest, the Location is pulled from the appointment. Otherwise, it is taken from the Client Details page. Box 32a is the facility NPI of the location. If unspecified, the Facility NPI of the organization is used.

Box 33 is a bit of a doozy. The first bit is the Billing Provider name and location. This depends on the Billing Provider and Provider’s location as specified in the invoice details of the claim. The billing provider address values and phone number are taken from the “Send Payments To” section of your organization settings. If this section is empty, then the Location address is used. Billing Provider Name is used if the “Bill with Selected Staff NPI” box is checked in the invoice details and the provider is selected, otherwise the organization name is used.

33a contains the Billing Provider’s NPI, otherwise the organization’s NPI is used. 33b is constructed from the qualifier and ID Number entered in the Additional ID field of the Insurer Details, if applicable.


Oh my goodness you guys, that was a lot. The key takeaway here is that the information you put into your EHR system has a direct impact on how your CMS 1500 will be populated. In having a clearer picture of the elements of the CMS 1500 form, I hope that you feel more prepared to tackle insurance billing for your practice and overcome any claim denials that come your way.

I want to impress upon you how much we at TheraNest care about your ability to successfully and confidently approach the revenue cycle management of your practice. In TheraNest we have this fantastic feature throughout the system that shows a little icon next to every information field that populates on the CMS 1500 form. So, next to the client name field, for example, there’s a little CMS icon you can click on that will show a message that says “Populates Box 2 and 4 of the CMS form”. So handy, right? As a TheraNest subscriber, you also gain access to an entire library of help articles in our Knowledge Base to answer questions you have about the billing process. As I mentioned earlier in the episode, there is a written version of this podcast called CMS 1500 Claim Form Guide that can be found through that TheraNest Knowledge Base.

The TheraNest Billing Specialist team, myself included, are also here to support your insurance billing cycle through every step, from invoice creation to payment received. We are available every business day to answer your questions and help you work through any issues that may arise as you embark on your insurance billing journey.

If you are not yet a TheraNest subscriber but would like to change that, you can start by signing up for a free 21 day trial here. If are already part of the TheraNest family and want to start electronically billing through TheraNest, simply send us a message saying “Get Started with Billing” via the “Get Help” button in your account.

Thank you so much for listening to this episode of Billing Breakthroughs. I wish you all the best in your practice management! This is Sage from the Billing Specialist team and you have been listening to Billing Breakthroughs, a podcast devoted to helping you find billing success. Bye for now!