If an auditor walked into your chiropractic practice tomorrow and pulled ten Medicare charts, the document most likely to decide whether you keep that revenue probably is not your treatment note. It is a one-page notice you were supposed to hand the patient before treatment started — and since May 2026, it has to be the new version of that notice, or it may not count at all.
Here is the uncomfortable backdrop. Medicare's error-rate testing has repeatedly found that roughly one in three dollars paid for chiropractic services is an improper payment — the November 2025 supplemental data put the chiropractic improper-payment rate at 30.4%, with almost 90% of those errors chalked up to insufficient documentation. That makes chiropractic one of the most documentation-scrutinized corners of Part B, and it is why auditors keep coming back. Against that background, the Centers for Medicare & Medicaid Services (CMS) released an updated Advance Beneficiary Notice of Noncoverage (Form CMS-R-131) on March 13, 2026, and required every fee-for-service provider to switch to it no later than May 12, 2026.
If your front desk is still handing out the old form with the January 2026 expiration date, those notices are now stale. And a stale or defective notice is treated the same as no notice at all — which means denied claims come out of your pocket, not the patient's. This guide explains what the form does, what changed, where chiropractic practices are most exposed, and how to build a workflow plus bookkeeping routine that holds up under audit.
What an ABN Actually Does for Your Practice
The Advance Beneficiary Notice of Noncoverage is Medicare's liability-shifting device. When you have reason to believe Medicare will deny payment for a service that Medicare otherwise covers — because it may not meet the "reasonable and necessary" standard, because frequency limits may apply, or because the documentation may not support coverage — you issue the ABN before furnishing the service. The patient reads it, chooses whether to proceed self-pay, and signs.
The economics are blunt:
- Valid ABN on file + Medicare denies → the patient owes you. You preserved your right to bill the beneficiary.
- No ABN, or a defective ABN + Medicare denies → you absorb it. You generally cannot bill the patient and must write off the charge.
That second line is where practices bleed. Every denied visit without a valid notice converts a revenue event into a loss event with no recourse. For a practice with heavy Medicare volume, a handful of those a week compounds into tens of thousands of dollars a year in unbillable care you already delivered.
Three things an ABN does not do, because getting these wrong creates its own enforcement risk: it does not let you charge a patient for a service Medicare actually covers; it does not let you bundle covered services into membership, access, or administrative fees; and routine "defensive" ABNs issued for every visit regardless of denial risk are not permitted and can themselves draw scrutiny.
What Changed in 2026 — and Why the Deadline Already Matters
The March 2026 update is framed as a usability refresh: clearer language for beneficiaries and less burden on providers. The substantive rules did not change. But two facts make this update operationally urgent rather than cosmetic:
- The transition deadline has passed. Providers were required to move to the new form by May 12, 2026. Notices issued on the superseded version after that date risk being treated as invalid.
- Invalid means provider-liable. An ABN that is incomplete, delivered too late (at or after the time of service), or pre-filled with an option selected on the patient's behalf is treated as though no ABN was issued. The financial risk of the denial lands on you.
For the new form to protect you, every notice must identify the specific items or services at issue, state in plain language why Medicare may not pay for each one, include a good-faith cost estimate, and be delivered far enough in advance that the patient can genuinely consider the options. Your staff must also review it verbally with the patient and answer questions — sliding a form across the counter for a signature does not satisfy the requirement.
If you have not already done so, pull every ABN template in your office this week: paper pads at the front desk, PDFs in your EHR, scanned copies in your document library. Anything showing the old expiration date needs to go.
Why Chiropractic Practices Sit in the Audit Spotlight
Medicare covers exactly one chiropractic service under Part B: manual spinal manipulation to correct a subluxation. Everything about your audit exposure flows from that narrow grant of coverage.
Active treatment is covered. Maintenance therapy is not.
Active treatment means the patient has a significant neuromusculoskeletal problem, you expect reasonable improvement, and you are working from a plan with frequency, duration, and goals. Maintenance therapy means the condition has plateaued, care is supportive, and no further improvement is expected. Medicare pays for the first and never for the second — and the boundary between them runs through the middle of a typical episode of care. The patient who improves for six visits and then plateaus crosses from covered to non-covered mid-plan, often without anyone announcing it.
The AT modifier is a flag, not a shield
You append the AT modifier to CPT codes 98940, 98941, and 98942 to indicate active, corrective treatment. Claims without it are treated as maintenance and denied. But the modifier alone proves nothing: your notes must still show the subluxation, its link to the symptoms, the treatment plan, and measurable progress. Federal watchdogs have found the modifier to be a weak safeguard precisely because practices attach it while the documentation underneath describes maintenance care. An auditor reading "patient feels better, continue same plan" with an AT modifier on the claim sees a mismatch, not compliance.
Same-day E/M plus adjustment stays on the radar
Billing an evaluation-and-management visit on the same day as a manipulation is legitimate when a separately identifiable, significant evaluation occurred — a new problem, a re-examination that changes the plan, a complex case. But the note must read as two distinct pieces of work. One blended paragraph covering both the eval and the adjustment invites the auditor to disallow the E/M every time.
The errors are documentation errors
Across every error-rate report, the story is the same: the dominant failure is insufficient documentation, not wrong code selection. Your biggest risk is not picking 98941 instead of 98940. It is failing to show, visit after visit, the subluxation, the plan, and the progress.
Where the ABN Fits in a Chiropractic Workflow
For most chiropractic offices, ABN trigger points cluster around three moments:
1. The active-to-maintenance transition. When objective measures plateau and further improvement is unlikely, covered care is ending. If the patient wants to continue on a supportive schedule, that is precisely the conversation the ABN exists for: Medicare will likely deny, here is the cost, do you want to proceed self-pay? Issue it before the first maintenance visit, not three visits in.
2. Frequency and duration expectations. When a plan extends beyond what is typical for the condition — the twelfth visit for an uncomplicated episode, say — the denial risk rises even while care is still nominally active. A signed notice preserves your options if the contractor disagrees with your judgment.
3. Same-day E/M uncertainty. If you are billing an E/M alongside the adjustment and the separate medical necessity is debatable, an ABN covering the E/M portion means a denial of that line does not become your loss.
Each trigger should be a defined step in your visit workflow with a named owner — typically the treating doctor identifies the trigger and the front desk executes the notice before the patient reaches the treatment room. "The doctor will mention it" is not a workflow. A checkbox on the encounter form, initialed by whoever delivered the notice, is.
The Claim Modifiers That Make the ABN Count
The notice alone does not tell Medicare what happened. The modifiers on the claim do. Get these right or the ABN cannot do its job:
- GA — signed ABN on file. Append it to the CPT line when you expect a reasonable-and-necessary denial and hold a valid signed notice. Medicare reviews for medical necessity, and if it denies, liability assigns to the patient, who receives a notice confirming responsibility. No GA modifier, no patient billing — even with a perfect ABN in the drawer.
- GZ — no ABN, expecting denial. Use this when you expect a denial but did not obtain a notice. The claim will be denied with liability on you. Its honest function is analytics: GZ lines in your billing reports show you exactly where valid ABNs should have been issued.
- GY — statutorily excluded service. For services Medicare never covers by statute, where an ABN is optional. Routine use in chiropractic billing is narrow, but it belongs in your chargemaster correctly configured rather than improvised per claim.
- GX — voluntary notice for non-covered services. For a signed notice covering services outside Medicare benefits, where Medicare assigns patient liability without a medical-necessity review.
A monthly report of GA versus GZ lines is one of the cheapest audit-risk dashboards a practice can run. Rising GZ volume means your trigger workflow is leaking; every GZ line is a visit you delivered at your own expense by default.
The Bookkeeping Half Nobody Talks About
ABN-protected revenue behaves differently from ordinary insurance revenue, and your books should reflect that. Three habits separate practices that collect on their notices from practices that hold signed forms they never convert to cash:
Track ABN self-pay receivables separately from insurance A/R. A signed ABN creates a patient obligation contingent on denial. If those balances sit in the same bucket as insurance claims, they age invisibly until they are uncollectible. A separate ledger or A/R class — ABN-pending, ABN-denied-and-billed, ABN-paid — lets you see conversion rates and follow up while the balance is fresh.
Reconcile GA lines to cash every month. For each claim line billed with a GA modifier, there are only three lawful endings: Medicare paid it, Medicare denied it and the patient paid, or Medicare denied it and you wrote it off after good-faith collection. Any GA line that matches none of these is a bookkeeping gap. Run the reconciliation monthly, not quarterly — denied ABN balances go stale fast, and timely patient statements are the difference between collected and written off.
Keep denied-without-ABN write-offs visible. GZ-driven write-offs are contractual adjustments in substance: revenue you earned clinically and surrendered administratively. Burying them in a generic adjustments account hides the cost of your workflow failures. A distinct adjustment code makes the monthly total a management metric — if it climbs, fix the trigger workflow before you hire a biller to chase balances you were never allowed to bill.
The same discipline applies to your code libraries. The FY 2026 diagnosis update (effective for encounters on or after October 1, 2025) added hundreds of new codes with finer detail for pain, contusions, and comorbidities, while the 2026 CPT set touched hundreds of codes around E/M, telehealth, and time-based rules. Your core manipulation codes did not change — but the codes around them did. Refresh EHR pick-lists and paper superbills so clinicians select current codes by default, retire deleted ones so nobody can select them by habit, and never let dates of service straddle the October 1 boundary with the wrong code year. Every coding error that produces a denial without an ABN on file is another visit you financed yourself.
Train the Team on Five Things
You do not need a compliance department. You need every person who touches a Medicare visit to know these five things cold:
- The difference between active and maintenance care — and that the transition mid-episode is the highest-risk moment in the chart.
- When to attach the AT modifier and when to remove it.
- The three ABN trigger points and who owns each step of the notice workflow.
- What makes a notice valid: specific service, plain-language reason, good-faith estimate, advance delivery, verbal review, patient-selected option.
- Which claim modifier follows which scenario — GA, GZ, GY — and that a signed ABN without the GA modifier cannot produce a patient bill.
Walk through five to ten of your own recent Medicare cases with the team, including at least one maintenance-transition case. Abstract training fades; your own charts stick.
Get Ahead of the Next Audit Instead of Reacting to It
The practices that survive Medicare scrutiny share one trait: compliance lives in the daily workflow, not in a binder. The new ABN form is already mandatory. The error rate on chiropractic claims remains among the highest in Part B. Documentation pressure is rising through code updates and active-treatment enforcement at the same time.
Start with the form swap, define your three trigger points, wire the GA/GZ modifiers to your billing, and reconcile the results monthly. None of this requires new software — it requires a workflow your team actually follows and books that actually show what happened.
Simplify Your Financial Management
As you tighten Medicare compliance, keeping clean, auditable financial records for the whole practice matters more than ever — ABN receivables, denial write-offs, and adjustment trends all need to reconcile to books you can trust. Beancount.io offers plain-text accounting that is transparent, version-controlled, and AI-ready, so your practice finances stay as organized as your charts. Get started for free and see why professionals who live in the details are switching to plain-text accounting.
