Signature Requirements: The Simple Rule That Voids a Medicare Claim (42 CFR § 424.507)

Signature requirements look deceptively simple, yet many small practices discover the hard way that a missing or illegible signature can void a Medicare claim. Under 42 CFR 424.507, payment for certain services depends on being able to identify and verify the enrolled practitioner who ordered or referred the service. If a contractor cannot connect a claim to a properly authenticated order or medical record entry, the result is often denial or recoupment. 

Medicare claims reviewers rely on signed and dated documentation to determine that services were actually ordered or provided by an eligible practitioner, and to meet the broader requirement in the Social Security Act that no payment is made without the information needed to process the claim.  Signature rules are enforced not just in audits, but in routine medical review, CERT sampling, and targeted probes, and small clinics are particularly vulnerable because one provider’s poor habits can impact the entire cash flow. 

This article explains how signature requirements connect to the ordering and referring rules in 42 CFR 424.507, how contractors apply the Medicare Learning Network guidance on valid signatures, and how a small practice can put in place low cost controls that prevent avoidable denials. It also provides a practical self audit checklist and highlights the most common signature related technical mistakes that small practices make.

For many clinicians, signatures are an afterthought. They finish their note or write an order, move on to the next patient, and assume that their scribble somewhere in the chart is “good enough.” For Medicare, “good enough” has a very specific meaning. Claims reviewers need to see a signature that they can reasonably attribute to a particular enrolled practitioner, on documentation that shows what was ordered or provided and when. 

For services governed by the ordering and referring provisions in 42 CFR 424.507, such as imaging, certain lab tests, and some DME items, payment is contingent on being able to identify an eligible, correctly enrolled practitioner as the source of the order or referral.  If your documentation is missing signatures, has undated signatures, or uses formats that do not meet Medicare rules, auditors may conclude that they cannot verify who ordered the service or whether the order existed at all at the time of service.

Small practices often lack compliance staff and rely on one biller or office manager to catch problems. This is risky. A single pattern of unsigned diagnostic test orders or unauthenticated progress notes can trigger extrapolated recoupments and ongoing monitoring. The goal is not to turn every clinician into a compliance lawyer, but to implement a few rigid habits so that, when Medicare or a contractor pulls charts, every order and progress note is clearly tied to a signed and dated entry from an eligible practitioner.

Understanding Legal Framework and Scope Under 42 CFR 424.507

42 CFR 424.507 sits inside the broader Medicare enrollment and participation rules in 42 CFR Part 424. It addresses payment for certain Medicare Part B services that require an order or referral. For those services, Medicare will not pay unless the ordering or referring practitioner is properly identified and meets the enrollment conditions. 

While 42 CFR 424.507 focuses on ordering and referring, it works in tandem with other legal requirements. Section 1833(e) of the Social Security Act states that no Medicare payment can be made unless any information required to determine the amount of the payment has been submitted.  If contractors cannot verify who ordered or provided services because your documentation lacks a valid signature, they may conclude that the required information is incomplete and deny the claim or recoup the payment.

CMS operationalizes this framework through subregulatory guidance, especially the Medicare Program Integrity Manual and the MLN fact sheet “Complying With Medicare Signature Requirements.” These sources define what counts as a valid signature: generally, a handwritten or electronic mark made by the ordering or prescribing physician or non physician practitioner that signifies knowledge, approval, acceptance, or obligation, and that can be associated with the documented service. 

Federal rules set the floor. States may add additional documentation requirements for medical records or prescribe rules for electronic signatures, but those do not replace the basic Medicare conditions for payment. Understanding how 42 CFR 424.507 and related guidance interact allows a small practice to align its documentation habits with federal expectations, reducing the risk of technical denials, overpayment demands, and administrative friction with MACs and other contractors.

Several entities share responsibility for enforcing Medicare signature requirements that flow from 42 CFR 424.507 and related authorities. CMS sets the underlying regulations and issues national guidance. Medicare Administrative Contractors apply those rules in day to day claims processing and medical review, including determining whether your documentation supports the identity and enrollment status of the ordering practitioner. 

Program integrity contractors such as CERT, Recovery Audit Contractors, and Unified Program Integrity Contractors conduct deeper reviews to measure improper payment rates and detect patterns of noncompliance. Their reports consistently highlight missing or invalid signatures as a cause of improper payments. 

Common audit and review triggers tied to signature requirements include:

• Unusual billing patterns for specific diagnostic tests where ordering information is weak or inconsistent.

• CERT sampling that flags charts with unsigned orders or undated notes supporting billed services.

• DME or imaging claims where the ordering practitioner’s enrollment status cannot be verified, suggesting inadequate documentation of who ordered the item or service.

• Repeated use of stamped signatures or generic electronic signature lines that do not clearly identify the responsible practitioner.

When reviewers encounter these patterns, they are authorized to deny claims or recoup previous payments, especially if they cannot tie the billed services back to an enrolled ordering or prescribing practitioner. For a small practice, even a modest sample of denied claims can create cash flow stress and potential reputational harm with payers.

This survival guide focuses on concrete controls a small practice can use to meet signature expectations that support 42 CFR 424.507, using minimal budget and staff time. Each control includes implementation steps, evidence to retain, and a low-cost option.

1. Standardize signature formats in the EHR

   Begin by defining a standard format for electronic signatures that includes the practitioner’s name and credentials, and ensures that every signed entry is time and date stamped. Configure your EHR so that each user’s signature block is unique and tied to their login, and disable generic shared logins.

   Evidence: Screen captures of user signature settings and sample signed notes demonstrating the standard format.

   Low cost approach: Use built in EHR tools to configure signatures rather than purchasing add-ons. If you still use some paper records, attach a simple signature reference sheet showing each practitioner’s handwritten signature next to their printed name.

2. Create and maintain a practice wide signature log

   A signature log is a typed list of physicians and non physician practitioners showing their names alongside their handwritten signatures and, optionally, credentials. CMS encourages this tool and reviewers rely on it to interpret illegible signatures.

   Implementation: Build a one-page log for the practice, gather handwritten signatures from each practitioner, and confirm that the printed names match the names used in your EHR and on Medicare enrollment files. Update the log when clinicians join or leave.

   Evidence: The signed log itself stored in a shared compliance folder, plus periodic review notes confirming it remains current.

   Low cost approach: Create the log using a basic word processor and store a scanned copy on your shared drive and in your EHR’s administrative library.

3. Use a pre billing signature completeness check

   Before submitting Medicare claims for services that require an order or clear practitioner documentation, your biller or designated staff member should verify that each chart includes a signed and dated order or note. This check is particularly important for imaging, lab tests, and DME subject to 42 CFR 424.507.

   Implementation: Add a “signature complete” column to your internal billing or tracking report. The biller marks “yes” only after confirming that an appropriate practitioner signature is present and legible or supported by a log.

   Evidence: Saved copies of tracking reports showing the signature check and occasional audit notes where missing signatures were identified and corrected before submission.

   Low cost approach: Use a shared spreadsheet or your practice management system’s notes field to track this check, rather than buying new software.

4. Implement a “no unsigned orders” rule for diagnostic services

   For orders that must be signed before services are performed, such as many diagnostic tests and DME items, unsigned orders cannot generally be fixed with attestations after the fact.

   Implementation: Train front desk and clinical staff not to schedule or perform certain services until they see a signed order or a signed progress note clearly documenting the order. Provide a simple reference list of services in this category.

   Evidence: Training agendas and sign in sheets, plus spot audits showing that orders were signed before service dates.

   Low cost approach: Maintain the reference list as a simple one-page laminated sheet at scheduling desks and nursing stations.

5. Use signature attestations only when allowed and tracked

   Attestations can sometimes rescue documentation where a required signature on medical documentation (but not on a required order) is missing. CMS allows the author to submit a signed statement attesting that they created the entry, but not to create retroactive orders.

   Implementation: Keep a standard attestation template that includes the practitioner’s name, a statement linking the attestation to a specific record, and the date. Track when attestations are used and periodically review them to see if certain clinicians need extra training.

   Evidence: Copies of completed attestations attached to the relevant records and maintained in a separate attestation folder.

   Low cost approach: Use a one-page template that can be printed or electronically signed, without purchasing any additional tools.

Together, these controls create a repeatable system that makes every order and key clinical record traceable to an identifiable, enrolled practitioner, satisfying the operational expectations behind 42 CFR 424.507 and reducing your vulnerability to technical denials.

Case Study

A small imaging heavy internal medicine clinic relied on a senior physician whose handwriting had become increasingly difficult to read. He signed every order and progress note, but his signature was essentially an illegible squiggle. The clinic did not maintain a signature log and had not standardized its EHR signatures. When a CERT audit pulled a sample of claims for diagnostic tests, reviewers could not confirm who had ordered several services. 

Because the audit focused on services that require a valid order from an enrolled practitioner under the ordering and referring rules in 42 CFR 424.507, the lack of a readable signature created a problem. The contractor concluded that the clinic had not provided adequate documentation to show who ordered the tests, triggering denials and an extrapolated overpayment that ran into tens of thousands of dollars.

Financially, the clinic faced a large recoupment and had to divert limited staff time to assembling additional documentation. Legally, the pattern of documentation deficiencies raised concerns that could invite further scrutiny from program integrity contractors. Reputationally, the clinic’s relationship with Medicare and certain referring physicians deteriorated as payment delays mounted.

After consulting with its compliance adviser, the clinic implemented a signature log, standardized electronic signatures in the EHR, and instituted a pre billing signature completeness check. When a subsequent audit occurred two years later, reviewers again questioned legibility but quickly accepted the signature log and the EHR signatures as sufficient evidence that the enrolled physician had ordered the services. No overpayment was assessed, and the clinic’s claim error rate dropped. The same simple controls that would have cost almost nothing to adopt at the beginning ultimately prevented repeat technical denials under the 42 CFR 424.507 ordering and referring framework.

These tasks give a small practice a compact but powerful way to confirm that signatures supporting ordered and referred services are complete, legible, and traceable to enrolled practitioners, which is central to avoiding denials under 42 CFR 424.507.

Common Audit Pitfalls to Avoid Under 42 CFR 424.507

When contractors review charts for compliance with ordering and referring requirements, a predictable set of signature related mistakes appears. Understanding these pitfalls helps your clinic focus its limited energy on the highest risk behaviors.

• Relying on illegible signatures without a supporting log. Reviewers may be unable to verify that an enrolled practitioner ordered or provided the service, leading to denials under the ordering and referring rules.

• Using stamped signatures without a documented disability exception. CMS generally disallows stamped signatures for medical records and orders, so claims supported only by stamps may be treated as unsupported.

• Allowing unsigned orders for diagnostic tests that require a signed authorization before the service. When an order must exist and be signed before a service is performed, contractors usually will not accept later attestations, and payment may be denied.

• Failing to date signatures or relying on surrounding dates that do not clearly establish when the order was made. If reviewers cannot determine whether the order existed at the time of service, they may treat the claim as unsupported.

• Using shared EHR logins that make it impossible to prove which practitioner signed a note. Shared accounts undermine the ability to link an order to an enrolled ordering practitioner, which is central to 42 CFR 424.507 compliance.

• Ignoring contractor requests for signature logs or attestations or responding late. Contractors often provide specific deadlines for supplying these documents, and missed deadlines can convert a fixable documentation gap into a permanent denial.

By targeting these errors, a small practice can significantly reduce the risk that technical deficiencies in signature practices will be treated as failures to meet ordering and referring requirements under 42 CFR 424.507, thereby lowering denial and recoupment rates.

Signature compliance is easiest to sustain when it is woven into daily operations instead of treated as a one time project. Assign clear ownership by designating a signature compliance lead, often the practice manager or billing supervisor, who tracks signature related issues and coordinates with clinicians.

Build signature expectations into onboarding and periodic training. New clinicians should receive a short orientation on how signatures support ordering and referring rules, along with demonstrations of how to sign orders and notes correctly in the EHR. Existing staff can review real examples from internal audits to see how small errors create large problems. 

Monitoring should remain simple. A quarterly dashboard might include the number of charts failing internal signature checks, the number of attestations used, and any signature related audit findings. When trends worsen, leadership can intervene quickly with targeted coaching instead of waiting for an external audit to reveal the problem.

For small practices, signature requirements may feel like a minor administrative detail, but under the legal framework supported by 42 CFR 424.507 and related Medicare guidance they can decide whether a claim is payable at all. If an auditor cannot tie diagnostic tests, DME, or other ordered services to an identifiable, enrolled practitioner through a valid signature, the services may be treated as never ordered for payment purposes.

The good news is that preventing these technical denials does not require expensive software or a large compliance department. A disciplined combination of standardized signatures, a maintained signature log, pre billing checks, and careful use of attestations can close most gaps. By embedding these practices into everyday workflows and monitoring basic metrics, small clinics can protect their revenue and demonstrate good faith compliance during audits.

Immediate next steps for a small clinic might include:

1. Build or update a signature log this week and store it in a central location that billing and compliance staff can access.

2. Review EHR signature settings for each practitioner to ensure that names are correctly displayed and that signatures are automatically dated and time stamped.

3. Add a signature completeness check to your pre billing process for all Medicare claims tied to ordered services.

4. Create a simple, approved attestation template and train clinicians on when it may be used, with an emphasis that it cannot replace required pre-service orders.

5. Plan a small internal audit of recent diagnostic test claims to confirm that each one is supported by clearly signed and dated orders or notes from enrolled practitioners.

Recommended compliance tool: 

A combined “signature control pack” consisting of a log template, attestation template, and a simple pre billing checklist kept in your shared drive.

Advice: Pick one upcoming day’s Medicare claims and verify that every ordered service is supported by a signed and dated order or progress note from an enrolled practitioner before you submit those claims.

• Complying With Medicare Signature Requirements MLN Fact Sheet (ICN 905364)
  

• Medicare Program Integrity Manual, Publication 100 08, Chapter 3, Signature Requirements Sections
  

• Social Security Act Section 1833(e) Payment of Benefits
  

• Complying With Signature Requirements for Diagnostic Tests Fast Facts
  

• Noridian Medical Documentation Signature Requirements Summary