Using a CMS IOM (Internet-Only Manual): Research Guide

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Written by Katherine Zheng, PhD, BSN Content Writer, IntelyCare
Two nurses using the CMS IOM.

Government regulations play a key role in shaping patient care standards and reimbursement policies. For facility administrators and healthcare providers, maintaining regulatory compliance requires staying up to date with the latest information. The CMS IOM repository is a great resource for this, providing quick access to comprehensive guidelines directly from the Center for Medicare and Medicaid Services (CMS).

But, what exactly are IOMs and how do you use them? We’ll detail everything you need to know before you sift through these regulatory documents.

What Is a CMS IOM?

The CMS Internet-Only Manual (IOM) is an online repository of official guidelines that provide information about the administration of Medicare and Medicaid programs. It’s updated regularly to reflect changes in laws, policies, and regulations that impact facilities participating in these programs.

The CMS internet-only manuals cover a range of topics, including:

  • CMS program eligibility criteria
  • Reimbursement guidelines
  • Billing and coding policies
  • Quality improvement guidance
  • CMS program details

How Do You Navigate the CMS IOM Repository?

CMS provides access to IOMs directly on their website. Not all manuals will be relevant to your facility’s operations, so you may need to filter through the options to find one that covers a topic you’re interested in.

Here are some basic steps you can follow to navigate the IOM repository:

  1. Visit the IOM web page
  2. Scroll through the manual titles or use the “Filter On” function to search for keywords
  3. Click the manual that is most relevant to your question
  4. Scroll down the table of contents to find specific chapter topics
  5. Click the chapter that covers your topic of interest


To understand how navigating the IOM web page works in practice, we can use billing as an example topic. Let’s say that you’re a hospital administrator looking for more information on how to bill for inpatient Medicare services. Scrolling through the repository 100-04: Medicare Claims Processing Manual looks like it would be most relevant to your query.

After clicking on this manual, the following chapters appear on the table of contents page (list is truncated for purposes of this example):

  • Chapter 1 – General Billing Requirements
  • Chapter 2 – Admission and Registration Requirements
  • Chapter 3 – Inpatient Hospital Billing
  • Chapter 4 – Part B Hospital (Including Inpatient Hospital Part B and OPPS)

Based on the first few chapters, Chapter 3 – Inpatient Hospital Billing appears to be the most specific to inpatient billing procedures, so this would serve as a good starting point as you conduct your research.

How Do You Read an IOM?

Once you find the manual and chapter most relevant to your needs, you can begin sorting through the information in the manual. When you click on a chapter, you’ll be brought to another table of contents inside the manual showing the chapter’s subsections. Each subsection is titled and hyperlinked, so clicking on relevant titles will bring you directly to the corresponding information.


Continuing with the same billing example as above, we can walk through how you might begin reading Chapter 3 – Inpatient Hospital Billing. Upon clicking this chapter, the first few subsections on the table of contents appear as follows:

  • 10 – General Inpatient Requirements
  • 10.1 Claims Format
  • 10.2 Focused Medical Review (FMR)
  • 10.3 Spell of Illness
  • 10.4 Payment of Non Physician Services for Inpatients
  • 10.5 Hospital Inpatient Bundling

Reading the introduction section of any chapter is always a helpful way to get a broad overview of the information you’re seeking. In this case, 10 – General Inpatient Requirements would be your introductory starting point of reference.

If you’re more specifically seeking guidance on how to bill for medical items, you’ll want to click section 10.4 Payment of Non Physician Services for Inpatients after reading the introduction. This section outlines all of the medical items, supplies, and services that are eligible to be billed for under Medicare.

General Tips on Using the CMS IOM

While there is no one-size-fits-all approach to using the CMS IOM, there are a few general tips that can help you read through the information more efficiently.

  • Have a topic in mind: There’s a lot of information covered in the manuals, and it can help to have a specific topic in mind when you visit the repository. This will help you identify keywords as you navigate through the manual titles, chapters, and subsections.
  • Check references: Sometimes, one chapter of a manual may reference other chapters or manuals that add more context to the information you are looking for. It can help to read these as well to gain a more comprehensive understanding of the topic at hand.
  • Reach out for guidance: Since IOMs are regulatory documents, you may not know all the terms and phrases when you begin reading a section. If you need help with interpretation, you can always contact a CMS representative for additional guidance.
  • Regularly check for updates: Regulations can change from year to year, so it is important to revisit the manuals regularly to make sure you are utilizing the most up-to-date practices.

Looking For More Resources on Regulatory Compliance?

Now that you’ve learned how to use the CMS IOM, you may be wondering what other resources can help you stay compliant with relevant laws and policies. With Intelycare’s free newsletter, you’ll get updates on all of the latest regulatory guidelines relevant to your facility’s operations.