ABA Billing Guidelines: Codes, Units, Documentation, Payers

"ABA billing guidelines" sounds like one rulebook. There is not one. There is a code set owned by the AMA, a body of payer policy that differs by plan and state, a documentation standard your notes must meet, and an authorization that limits what you may bill. This guide lays out how those pieces fit together, in the order a claim is built. It is education, not billing advice, and it is as of November 2, 2026.

Step 1: The authorization comes first

Many ABA payers require prior authorization for assessment and treatment, and a claim for a service outside the authorization will usually deny. What to check on every authorization:

• Codes. Each authorized code, not just a total number of hours.
• Units and period. Units per code, the start and end dates, and whether the limit is weekly, monthly or per authorization period.
• Who. The authorized rendering or supervising provider, where the payer names one.
• Where. Place of service limits such as clinic, home or school.

Authorizations are payer-specific. Some payers authorize in hours per week, others in units per code. Treat the approval letter, not your schedule, as the source of truth, and compare scheduled units to remaining authorized units before the week starts rather than after the denial arrives. Our authorization tracking page describes how software can do that comparison.

Step 2: Choose the code the service actually met

The adaptive behavior codes are reported per 15 minutes. As of the ABA Coding Coalition's September 11, 2026 conversion table, the current set and what it becomes on January 1, 2027 is:

Service	2026 code	2027 code
QHP assessment and treatment planning	97151	97151
Technician supporting assessment	97152	97152
Harmful behavior supporting assessment, two or more technicians	0362T	97148 plus +97149
Technician treatment by protocol, one patient	97153	97153
Technician group treatment	97154	97154
Harmful behavior treatment, two or more technicians	0373T	97159 plus +97160
QHP treatment or direction of technician	97155	97155 (direction only) and 97173 (QHP treats alone)
Family guidance	97156	97156
Multiple-family group guidance	97157	97157
QHP group treatment	97158	97158
QHP non-face-to-face work	Not reportable	97180

Our ABA CPT codes reference lists these, and the guide to the 2027 code changes explains the transition. Two rules worth internalizing now because they hold in both years: only the face-to-face time that meets a descriptor is billable for most codes (the Coalition's guidance says the mere presence of a patient during QHP activities does not make those activities billable), and the code must match the person who delivered the service.

Step 3: Count units from documented minutes

One unit is 15 minutes for the adaptive behavior codes. Three habits keep unit counts defensible:

1. Bill from the note, not from the schedule. A cancelled half hour or a late arrival changes the units even though the calendar did not.
2. Use the payer's rounding rule. How partial units round, and whether there is a minimum number of minutes for the first unit, varies by payer. Confirm it in the manual and apply it consistently.
3. Do not let two services share minutes. One provider cannot bill two codes for the same minutes, and concurrent billing between providers is limited by payer rules. NC Medicaid's October 12, 2026 bulletin under Clinical Coverage Policy 8F, for instance, says concurrent billing is allowed only in the exceptions its attachment lists, and "All other concurrent billing is prohibited until further notice."

Step 4: Modifiers and provider data

Many payers want modifiers that show the education level of the person who rendered the service. The Coalition's conversion table notes that HM (high school), HN (four-year degree), HO (master's degree) and HP (doctoral degree) are commonly used with these codes; other modifiers cover telehealth or specific payer programs. Whether you need any, and which, is the payer's call.

Provider data causes its own denials. As a dated example, Maryland Medicaid's transmittal PT 76-26 (April 3, 2026) says that for dates of service from July 1, 2026, ABA claims must carry the NPI of an individual referring practitioner in Field 17b, that the referrer must be actively enrolled in Maryland Medicaid on the date of service, and that claims with a group or facility NPI will be denied. Few providers think of that as a billing guideline until a month of claims deny. Every state with a similar rule is another reason to keep referrer enrollment status in your intake checks.

Step 5: Documentation that supports the claim

The session note is what an auditor or payer reviewer reads. The Coalition's guidance repeatedly says documentation should be "consistent with payer policy requirements," and for 2027 adds that QHP analysis must be documented clearly. A sound note for a billed date of service shows:

• Date, start and stop times, and setting.
• Who delivered the service and in what role, with credentials.
• What protocol or goals were addressed, and the data collected.
• For QHP services, what the QHP did and what was decided, including a recorded decision when no change was needed.
• Who signed, and when, in line with payer and state signature rules.

Our guide to writing ABA session notes covers the note itself in detail.

Step 6: Submit, post, and work what comes back

Submission is the shortest step and the least interesting. What matters is the loop after it: post payments and adjustments to the right claim line, compare payment to the contracted rate, and work denials by reason code. Timely filing limits, resubmission windows and appeal deadlines differ by payer and are set in the contract or the state's manual; write them on your payer grid instead of discovering them on a denial. When denials do repeat, fix the cause upstream; our guide to reducing ABA claim denials goes cause by cause.

Rates also differ for the same code. Highmark's August 17, 2026 notice, for example, set commercial PPO rates for 97153 effective October 16, 2026 of $16.59 office and $15.73 non-office in Pennsylvania, $14.53 and $13.78 in West Virginia, and $15.73 in Delaware. That is one payer's example, not a benchmark.

Medicaid and commercial plans are different games

Medicaid ABA is run by state agencies and managed care plans, with state-specific manuals, provider enrollment and revalidation requirements, and fee schedules. Commercial plans follow their own medical policies and contracts. Each pairing adds its own authorization form, its own claim edits and its own timelines. If you bill state Medicaid, our Medicaid billing page covers how software handles that. The practical rule: keep a one-page payer grid for every plan you bill, listing authorization process, modifiers, rounding rule, referring provider requirement, concurrent billing limits, timely filing and the contact for escalations.

2027: what to prepare now

• 0362T and 0373T are invalid for dates of service on or after January 1, 2027, with no grace period (ABA Coding Coalition guidance).
• Payers are not all required to load the new codes on January 1 or to honor existing authorizations that name deleted codes; the Coalition encourages getting written confirmation from each payer.
• 97155 narrows and 97173 and 97180 appear, which changes both authorization requests and note templates.
• Your billing system, clearinghouse mappings and contracts all need the new codes; ask your vendors for their dates.

Where software helps, and where it does not

Software cannot change a payer's policy. It can keep authorization balances visible, tie units to completed sessions, and check a claim against rules before it leaves. Wilma, our platform, includes billing software with the claims workflow in Core, and AI claim scrubbing is part of Pro. It does not check payer eligibility; insurance information is captured at intake. Whatever you use, the guideline is the same: the authorization, the note and the claim have to agree.

A quick audit you can run this week

1. Pick ten recent claims across your two biggest payers. For each, confirm the authorization was active on the date and had units left for that code.
2. Check that the billed units match the documented minutes under the payer's rounding rule.
3. Check the rendering and referring provider data against the payer's requirements and the enrollment date.
4. Confirm the note is complete, signed and consistent with the code.
5. Confirm no two services share the same provider's minutes.

Every failure on that list is a denial waiting to happen, and each points to a specific process to fix.

Common mistakes

• Treating hours authorized as a single pool instead of units by code.
• Assuming one payer's modifier or rounding rule applies to all payers.
• Waiting for a denial to learn a payer changed a rule; read bulletins as they arrive.
• Letting notes close late, so billing runs on incomplete records.
• Waiting until January to find out how 2027 codes will be handled.

Sources, with dates

• ABA Coding Coalition, 2027 CPT Code Crosswalk, September 11, 2026, and Supplemental Guidance, October 2026 (abacodes.org).
• Maryland Medical Assistance Program, ABA Transmittal PT 76-26, April 3, 2026.
• NC Medicaid, concurrent billing clarification, October 12, 2026.
• Highmark Provider News, 97153 reimbursement update, posted August 17, 2026.