Medicare requires ambulance suppliers to report two-character origin and destination modifiers on nearly all ambulance transportation claims. These modifiers identify where the patient was picked up and where the patient was transported, helping Medicare determine the appropriate reimbursement and verify coverage requirements.

The letter N represents a Skilled Nursing Facility (SNF). It is not a standalone modifier and must always be combined with another origin or destination code to create a valid two-character ambulance modifier, such as RN, NR, HN, or NH.

Modifier N is commonly used when transporting Medicare beneficiaries between an SNF and another covered location, such as a hospital, residence, dialysis facility, or physician’s office, when Medicare coverage requirements for ambulance transportation are met.

Modifier

Modifier Name

Skilled Nursing Facility (SNF)

Plain English Explanation

The letter N tells Medicare:

“The ambulance transport either started from or ended at a Skilled Nursing Facility (SNF).”

Modifier N identifies the patient’s pickup or destination as a Medicare-certified SNF rather than another type of healthcare facility.

Purpose of Modifier N

Modifier N is used to:

Identify Skilled Nursing Facilities involved in ambulance transports.
Distinguish SNFs from hospitals, residences, assisted living facilities, and physician offices.
Report accurate ambulance origin and destination information.
Support Medicare ambulance reimbursement.
Comply with CMS ambulance billing requirements.

Understanding Modifier N

Ambulance origin and destination modifiers always consist of two letters.

First Letter = Origin (Pickup Location)
Second Letter = Destination (Drop-off Location)

Modifier N may appear in either position.

Common Modifier Combinations

Modifier	Meaning
RN	Residence → Skilled Nursing Facility
NR	Skilled Nursing Facility → Residence
HN	Hospital → Skilled Nursing Facility
NH	Skilled Nursing Facility → Hospital
NJ	Skilled Nursing Facility → Freestanding ESRD Facility
JN	Freestanding ESRD Facility → Skilled Nursing Facility
NG	Skilled Nursing Facility → Hospital-Based ESRD Facility
GN	Hospital-Based ESRD Facility → Skilled Nursing Facility
PN	Physician’s Office → Skilled Nursing Facility
NP	Skilled Nursing Facility → Physician’s Office

What Is a Skilled Nursing Facility (SNF)?

A Skilled Nursing Facility is a Medicare-certified facility that provides skilled nursing care and rehabilitation services under the supervision of licensed healthcare professionals.

Examples include:

Medicare-certified SNFs
Rehabilitation nursing facilities
Post-acute skilled care facilities
Facilities providing skilled nursing and therapy services covered under Medicare Part A or Part B

Important: Modifier N is used only for Skilled Nursing Facilities. It should not be used for assisted living facilities, custodial care facilities, or residential care homes. Those locations are generally reported with Modifier E.

When to Use Modifier N

Use Modifier N when:

The ambulance transport begins at an SNF.
The ambulance transport ends at an SNF.
The patient requires medically necessary ambulance transportation.
Medicare coverage requirements are met.
The correct two-letter origin/destination modifier is reported.

When NOT to Use Modifier N

Do not use Modifier N when:

The facility is an assisted living or custodial care facility (use Modifier E, if appropriate).
The patient is transported to or from a hospital (use H).
The patient is transported to or from a private residence (use R).
Modifier N is reported alone.
The facility is not Medicare-certified as a Skilled Nursing Facility.

Medicare Rules

Under Medicare:

Modifier N must always be reported with another valid origin/destination code.
The first letter identifies the pickup location.
The second letter identifies the destination.
Documentation must support that the facility is an SNF.
Medical necessity for ambulance transportation must be established.
Incorrect facility classification or modifier selection may result in claim rejection or denial.

When billing ambulance transports involving SNF residents, providers should also be aware of the Medicare SNF Consolidated Billing rules, which determine whether the SNF or Medicare is financially responsible for certain services.

Commercial Insurance Rules

Many commercial insurers use the same ambulance origin and destination coding structure as Medicare.

However, commercial payer requirements may vary regarding:

Prior authorization.
Medical necessity criteria.
Covered destinations.
Ambulance reimbursement policies.
Documentation requirements.

Always verify payer-specific guidelines before submitting claims.

Documentation Requirements

Documentation should include:

Pickup address.
Destination address.
Name of the Skilled Nursing Facility.
Confirmation that the facility is Medicare-certified, when applicable.
Ambulance run report.
Medical necessity documentation.
Physician Certification Statement (PCS), if required.
Date and time of transport.
Mileage documentation.
Crew signatures.

Real Billing Examples

Example 1 – Skilled Nursing Facility to Hospital

A resident of a Skilled Nursing Facility develops acute respiratory distress and requires emergency transport to the hospital.

Billing

HCPCS A0427
Modifier NH
A0425 (Mileage)

Example 2 – Hospital to Skilled Nursing Facility

Following hospitalization, the patient is discharged back to the Skilled Nursing Facility.

Billing

HCPCS A0428
Modifier HN

Example 3 – Skilled Nursing Facility to Freestanding Dialysis Center

A patient receives scheduled dialysis at an independent dialysis clinic.

Billing

HCPCS A0428
Modifier NJ

Example 4 – Skilled Nursing Facility to Physician’s Office

A patient is transported for a medically necessary specialist appointment.

Billing

HCPCS A0428
Modifier NP

Example 5 – Incorrect Use

A provider submits:

A0428-N

This is incorrect because Modifier N cannot be billed by itself. Medicare requires a complete two-letter origin/destination modifier.

CMS-1500 Claim Example

Field	Example
HCPCS	A0428
Modifier	NH
Diagnosis Pointer	Appropriate ICD-10-CM diagnosis
Mileage	A0425 (if applicable)

Common Denial Reasons

Modifier N reported alone.
Incorrect origin/destination modifier.
Facility incorrectly classified as an SNF.
Missing ambulance run report.
Medical necessity not documented.
Missing mileage documentation.
Invalid modifier combination.
SNF Consolidated Billing issues.

How to Correct the Denial

Verify the facility type.
Confirm the pickup and destination locations.
Review the ambulance run report.
Verify compliance with SNF Consolidated Billing requirements.
Correct the origin/destination modifier.
Submit supporting documentation.
Resubmit or appeal when appropriate.

Coding Tips

Never report Modifier N by itself.
Confirm that the facility is a Skilled Nursing Facility, not an assisted living facility.
Verify the correct origin/destination sequence.
Review SNF Consolidated Billing requirements when applicable.
Ensure documentation supports medical necessity.
Maintain complete transport records.

Modifier N vs Modifier E

Modifier	Description
N	Skilled Nursing Facility
E	Residential, Domiciliary, or Custodial Facility

Modifier N vs Modifier H

Modifier	Description
N	Skilled Nursing Facility
H	Hospital

Modifier N vs Modifier R

Modifier	Description
N	Skilled Nursing Facility
R	Residence

Modifier N vs Modifier J

Modifier	Description
N	Skilled Nursing Facility
J	Freestanding ESRD Facility

Frequently Asked Questions (FAQs)

Q1. Can Modifier N be billed by itself?

Answer: No. Modifier N must always be paired with another valid ambulance origin/destination code.

Q2. What does Modifier N represent?

Answer: A Skilled Nursing Facility (SNF).

Q3. What does NH mean?

Answer: Skilled Nursing Facility → Hospital.

Q4. What does HN mean?

Answer: Hospital → Skilled Nursing Facility.

Q5. What is the difference between Modifier N and Modifier E?

Answer: Modifier N identifies a Skilled Nursing Facility, while Modifier E identifies a Residential, Domiciliary, or Custodial Facility, such as an assisted living facility.

AR Caller Tips

When following up on ambulance denials involving Skilled Nursing Facilities:

Confirm that the facility is a Medicare-certified SNF.
Verify the pickup and destination addresses.
Review the ambulance run report.
Check whether SNF Consolidated Billing applies.
Verify medical necessity.
Confirm mileage documentation.
Document the payer representative’s name, reference number, and appeal instructions.

Interview Questions

Question 1

What does Modifier N represent?

Answer: A Skilled Nursing Facility.

Question 2

Can Modifier N be reported alone?

Answer: No. It must always be paired with another valid ambulance origin/destination modifier.

Question 3

What is the difference between Modifier N and Modifier E?

Answer: Modifier N identifies a Skilled Nursing Facility, while Modifier E identifies residential, domiciliary, or custodial care facilities.

Question 4

What modifier is used for transport from an SNF to a hospital?

Answer: NH (Skilled Nursing Facility → Hospital).

Practice Scenario

Scenario

A Medicare beneficiary residing in a Skilled Nursing Facility develops altered mental status and is transported by emergency ambulance to the nearest hospital.

Question

Which modifier should be reported?

Answer

The correct modifier is NH, indicating Skilled Nursing Facility → Hospital.

Related Ambulance Modifiers

D – Diagnostic or Therapeutic Site
E – Residential, Domiciliary, or Custodial Facility
G – Hospital-Based ESRD Facility
H – Hospital
I – Site of Transfer Between Modes of Ambulance Transport
J – Freestanding ESRD Facility
P – Physician’s Office
R – Residence
S – Scene of Accident or Acute Event
X – Intermediate Stop at Physician’s Office (Destination Only)

Common Billing Mistakes

Reporting Modifier N alone.
Confusing an SNF with an assisted living facility.
Using the wrong origin/destination sequence.
Ignoring SNF Consolidated Billing rules.
Incomplete ambulance documentation.
Incorrect mileage reporting.

Key Takeaways

N represents a Skilled Nursing Facility (SNF).
It is not a standalone modifier.
It must always be combined with another valid ambulance origin/destination code.
SNFs should not be confused with assisted living or custodial care facilities.
Verify facility type, medical necessity, and SNF Consolidated Billing requirements before claim submission.

References

CMS Medicare Claims Processing Manual, Chapter 15 – Ambulance Services.
CMS Medicare Benefit Policy Manual.
CMS Ambulance Origin and Destination Codes Guidance.
Medicare Administrative Contractor (MAC) Ambulance Billing Articles.
HCPCS Level II Code Book.

Conclusion

The N ambulance origin/destination code identifies transports involving Skilled Nursing Facilities and is frequently used in Medicare ambulance billing. Proper use requires combining N with another valid origin/destination code, confirming that the facility is a Medicare-certified SNF, and maintaining complete documentation of medical necessity and transport details. Correct reporting helps ensure compliance with CMS requirements, minimizes claim denials, and supports accurate reimbursement.

Educational Disclaimer

This article was prepared with the assistance of artificial intelligence (AI) for educational and informational purposes. It is based on publicly available CMS guidance, Medicare ambulance billing principles, and general medical coding practices. It is not an official publication of CMS or the American Medical Association (AMA). Always consult the latest CMS Medicare Claims Processing Manual, HCPCS Level II codebook, Medicare Administrative Contractor (MAC) guidance, and payer-specific billing policies before coding, billing, or submitting claims.