An ambulatory surgery center can have a licensed building, a full surgical schedule and credentialed surgeons, and still be unable to bill Medicare for a single case. The reason is that ASC Medicare enrollment is not one application. It is a sequence of filings, a certification survey and a federal agreement, and the facility cannot be paid for services before the effective date CMS assigns at the end of that sequence.
This guide walks through each step in order: the CMS-855B, the survey route, the CMS-370 and CMS-377, realistic timelines, commercial and Medicaid payer credentialing, and the updates that keep the facility billing number active.
Enrollment, Certification and Credentialing: Three Separate Gates for an ASC
ASC Medicare enrollment, Medicare certification and payer credentialing are separate approvals from separate reviewers. A facility that treats them as one task usually discovers the gap when its first claims reject.
| Gate | Reviewed by | Outcome |
|---|---|---|
| Medicare enrollment (CMS-855B) | Part B MAC | Recommendation for approval |
| Medicare certification | State survey agency or CMS-approved accreditor; CMS decides | CMS agreement, CCN and effective date |
| Payer credentialing | Each commercial and Medicaid plan | Participation agreement and fee schedule |
Enrollment confirms the legal entity, owners and location are eligible to bill Medicare. Certification confirms the facility meets the ASC Conditions for Coverage in 42 CFR Part 416. Credentialing confirms each payer’s own participation standards.
This is different from individual provider enrollment. Surgeons and anesthesia providers enroll on their own applications and bill their professional services separately; if you need a refresher on how those terms differ, see our guide to provider credentialing vs. enrollment. This guide covers only the facility side: the ASC as a Medicare supplier billing the facility fee.
Preparing the CMS-855B: Sections ASCs Most Often Get Wrong
The CMS-855B is the enrollment application for Medicare suppliers, and ASCs file it with their Part B MAC through PECOS or on paper. Most development requests and rejections trace back to a few areas of the application rather than to the facility itself.
Identifying information and NPI
The legal business name and TIN must match the IRS records exactly, including punctuation and suffixes such as LLC. The ASC needs its own Type 2 organizational NPI, with an ambulatory surgical taxonomy, rather than a surgeon group NPI. A mismatch between NPPES, the IRS letter and the 855B is one of the fastest ways to trigger a development request.
Practice location
Report the physical address where surgery is performed, exactly as it appears on the state license. A PO box is not accepted as a practice location. If the ASC shares a building with a physician office, the suite must be clearly separated, and CMS does not allow an ASC to share space with a hospital outpatient surgery department.
Ownership and managing control
List every individual and organization with a 5% or greater direct or indirect ownership interest, plus managing employees and any management company. Physician-owned ASCs often have layered holding companies, and each layer must be disclosed. Missing owners are a common reason a MAC returns the application.
Final adverse legal actions
Disclose any final adverse actions for the entity, its owners and managing employees, such as exclusions, license revocations or prior Medicare revocations. Undisclosed history found during screening can lead to denial, not just a delay.
Application fee, EFT and signatures
Institutional suppliers, including ASCs, pay the Medicare application fee, which is $750 for calendar year 2026, at initial enrollment, when adding a location and at revalidation. Submit the CMS-588 electronic funds transfer form with the application, and have the authorized official sign. A missing fee or unsigned certification statement stops processing before review begins.
State Survey or Deemed Status: Choosing Your Certification Route
After enrollment, the ASC must prove it meets the Conditions for Coverage through an on-site survey. Surveyors use the protocols in Appendix L of the State Operations Manual, whichever route you choose.
| Factor | State survey | Accreditor (deemed status) |
|---|---|---|
| Surveyor | State health department for CMS | AAAHC, The Joint Commission, Quad A or ACHC |
| Cost | No survey fee | Accreditor fees |
| Scheduling | Lower CMS priority; some states are not scheduling initial surveys | After the MAC recommendation |
| Readiness proof | Operations letter and surgical log | Survey application and MAC letter |
| Oversight | State recertification surveys | Accreditor resurveys and CMS validation surveys |
For most new ASCs, deemed status is the faster and more predictable route because the survey date is not tied to the state backlog. The state route still makes sense where the state survey agency schedules initial surveys promptly and the ASC wants to avoid accreditation fees. Either way, the facility generally needs to be operational, which means performing cases it cannot yet bill to Medicare, so the survey date directly affects cash flow.
The CMS-370, CMS-377 and Supporting Documents After MAC Approval
Once the MAC reviews the CMS-855B, it sends its recommendation to the state survey agency, which assembles the certification packet for CMS. Two federal forms are submitted alongside the survey results, usually to the state agency, though some accreditors handle the CMS-377 for you.
| Form | Purpose | Sent to |
|---|---|---|
| CMS-855B | Medicare enrollment | Part B MAC |
| CMS-588 | EFT authorization | Part B MAC |
| CMS-370 | ASC agreement with CMS | State survey agency |
| CMS-377 | Request for certification | State agency or accreditor |
| Survey report | Proof of compliance | State survey agency |
Before the packet goes to CMS, confirm you have these supporting items on file:
- State ASC license, or proof the state does not require one
- MAC recommendation letter for the CMS-855B
- Signed CMS-370 with the legal entity name and the facility name
- Completed CMS-377
- Accreditation decision letter and full survey report, or the state survey results
- Accepted plan of correction for any deficiencies cited
CMS makes the final decision, issues the CCN and sets the effective date. Under 42 CFR 489.13, that date is generally the date the facility met all federal requirements, which can be the survey completion date or, when deficiencies were cited, the date an acceptable plan of correction was received. Cases performed before the effective date are not billable to Medicare as ASC facility services.
Realistic Timelines From Application to First Paid Claim
Most new ASCs should plan for several months between the first enrollment filing and the first paid Medicare claim. The MAC review is the most predictable stage; the survey and CMS final approval are where schedules slip.
| Stage | Typical timing | Common delay |
|---|---|---|
| Type 2 NPI | About 10 days | Name mismatch with IRS records |
| MAC review of the 855B | Up to about 60 days | Missing owners, fee or signature |
| Certification survey | Weeks (accreditor) to months (state) | Facility not yet operational |
| Plan of correction | Depends on deficiencies | Incomplete corrective action |
| CMS approval and CCN | Varies by CMS location | Incomplete survey packet |
| MAC final enrollment and PTAN | After CMS approval | 855B changes mid-process |
Three habits keep this timeline short. File the CMS-855B as soon as the license and ownership structure are final, answer every MAC development request within its deadline, and schedule the accreditation survey the day the MAC recommendation arrives. Our article on provider credentialing timelines and delays covers the response habits that apply to both facility and provider applications.
During the gap, hold Medicare claims for cases performed on or after the effective date until the PTAN is active, and track them against timely filing limits. Claims sent before the PTAN is loaded will reject, adding avoidable rework to accounts receivable, and cases performed before the effective date cannot be billed to Medicare at all.
Credentialing the ASC With Commercial and Medicaid Payers
Medicare certification does not enroll the ASC with any other payer. Commercial plans, Medicare Advantage plans and state Medicaid programs each require their own facility application, and most will not start review until the ASC can show its CCN and accreditation or state survey results.
A typical facility credentialing packet includes:
- State ASC license and CMS certification letter with the CCN
- Accreditation certificate and most recent survey report
- Type 2 NPI, W-9 and ownership disclosure
- General and professional liability certificates of insurance
- Medical staff roster showing that operating surgeons are credentialed and privileged at the facility
- Hospital transfer agreement or admitting privileges arrangement, where required
- CLIA certificate, if the ASC performs waived laboratory testing
Medicaid enrollment runs through the state Medicaid agency and often carries its own application fee and site visit. Medicare Advantage plans contract separately from traditional Medicare, so an ASC can be fully certified and still be out of network for a large share of local Medicare beneficiaries. For a side-by-side view of how Medicare and commercial credentialing differ, see payer-specific credentialing for Medicare vs. commercial insurance.
Negotiate the facility fee schedule during contracting, not after. Rates for high-volume CPT codes, implant and device reimbursement, and carve-outs should be in the agreement before the first commercial case is scheduled. Our guide to improving net collections with ASC medical billing explains how contract terms show up in collections.
Revalidation, Ownership Changes and Other Updates That Can Stop Payment
Approval is not permanent. An ASC must keep its enrollment record current, and missed updates are one of the most common reasons an established facility suddenly stops receiving Medicare payments.
| Event | Deadline | Risk if missed |
|---|---|---|
| Revalidation | Every 5 years (CMS lookup) | Billing privileges deactivated |
| Ownership, control or authorized official change | 30 days (42 CFR 424.516(e)) | Payment holds or revocation |
| Other enrollment changes | 90 days | Development requests |
| Accreditation renewal | Before expiration | Loss of deemed status |
| New practice location | Before seeing Medicare patients | Claims deny |
A change of ownership usually involves the MAC, the state survey agency and the accreditor at the same time, plus every commercial payer contract. Build the notification list before closing, not after, and confirm whether the buyer will accept assignment of the existing Medicare agreement. Revalidation also carries the Medicare application fee, so budget for it alongside accreditation renewals.
Conclusion: Plan the Effective Date Before You Plan the First Case
Every step in ASC Medicare enrollment feeds one date: the effective date CMS assigns after the CMS-855B, the survey and the CMS-370 and CMS-377 are complete. Facilities that file early, pick a survey route with a predictable schedule and start commercial and Medicaid credentialing in parallel reach their first paid claim months sooner than those that take each gate in turn. After approval, revalidation and ownership updates decide whether that billing number stays active.
If you are opening, acquiring or expanding a surgery center, MBW RCM can help. Our ASC billing services team coordinates facility enrollment and payer credentialing with clean claim submission, so the facility fee is billable from the first eligible date of service.
Frequently Asked Questions
Which Medicare enrollment form does an ambulatory surgery center use?
An ASC enrolls on the CMS-855B, filed with its Part B MAC through PECOS or on paper. The CMS-370 and CMS-377 are certification forms that follow the MAC recommendation; they do not replace the 855B.
Can an ASC bill Medicare for cases performed before certification?
No. Medicare pays ASC facility services only on or after the effective date CMS assigns. Cases performed earlier, including those done to show the facility is operational for the survey, cannot be billed to Medicare.
Is accreditation required for ASC Medicare certification?
No. An ASC can be certified through a state survey agency instead. Many facilities choose deemed status through an accreditor because initial state surveys are a lower priority and can take much longer to schedule.
Does the ASC application fee apply in 2026?
Yes. ASCs pay the Medicare application fee, $750 for 2026, at initial enrollment, when adding a practice location and at revalidation. A hardship exception can be requested with the application.
Do surgeons need separate Medicare enrollment to operate at the ASC?
Yes. Each surgeon and anesthesia provider enrolls individually, or through their group, to bill professional services. The ASC enrollment covers only the facility fee.
How often does an ASC revalidate its Medicare enrollment?
Every five years. Check the due date on the CMS revalidation list and submit before it; a missed revalidation can deactivate billing privileges.