An ABA authorization is a balance, not a permission slip. It names codes, a unit count and an end date, and every session either fits inside those three things or it does not. Practices that track only the expiration date learn about a unit shortfall from the remittance, weeks after the sessions were delivered.
What this covers
- Every adaptive behavior code bills in 15-minute units, so an hour is 4 units and a 20-hour week is 80 units.
- An authorization carries a start date, an end date and a unit total, and payers often approve that total by authorization class rather than by single code.
- Two triggers keep a case out of a gap: units consumed, counted weekly, and days remaining, counted against the packet’s own lead time.
- Progress data has to be current, within 30 days of the request in Maryland Medicaid, so a reauthorization packet cannot be assembled in the final week.
- Federal rules set the payer’s outside decision time at 7 calendar days standard and 72 hours expedited. That is a ceiling, not a planning number.
An authorization is a balance with an end date. Track what is left, not what was approved.units, dates and codes move on three different clocks
Units, dates and codes move on three different clocks. A 20-hour-a-week schedule spends about 346 units a month. An authorization can expire on a date nobody wrote on the appointment calendar. Assessment units are spent once and gone, while treatment units are consumed by every session that is delivered and documented.
Most practices hold the approval letter and the treatment plan, with no record in between. The register is that missing record: one row per authorization per code, carrying units approved, units billed, units left and the date the next request has to go in.
What an ABA authorization actually authorizes
Every code in the adaptive behavior family is a 15-minute unit. 97153 is one unit of direct treatment delivered by a technician under a behavior analyst’s direction. 97155 is one unit of supervision and protocol modification. 97156 is one unit of caregiver training. The conversion is fixed, and payers print it on their own forms: one unit is 15 minutes, four units are one hour.
The approval states three things that matter to billing, sometimes in three different places: a start date, an end date and a unit count. Maryland Medicaid’s ABA benefit, managed by Carelon Behavioral Health, authorizes services for a maximum of 180 days and requires a reassessment and a fresh preauthorization every 180 days for the length of treatment. The ABA Coding Coalition’s model coverage policy sets the benchmark the same way, holding that authorization periods should not run for less than 6 months.
| Code | What the unit covers | Daily maximum, Maryland Medicaid |
|---|---|---|
| 97151 | Assessment or reassessment by a psychologist, BCBA-D or BCBA, including the report and the treatment plan | 32 units |
| 97152 | Technician support during the assessment | 32 units |
| 97153 | Direct 1:1 treatment by protocol, delivered by a technician | 32 units, across up to three rendering providers |
| 97154 | Group treatment by protocol, 2 to 8 participants | 16 units |
| 97155 | Supervision and protocol modification, client present | 24 units |
| 97156 | Caregiver training, with or without the client present | 16 units |
| 97157 | Multiple-family caregiver training, 2 to 8 families | 10 units |
| 97158 | Group treatment with protocol modification | 10 units |
Carelon Maryland issues units by authorization class, not one code at a time. ABO covers the assessment, ABT covers 97153 and 97154, ABR covers 97155, and ABH covers 97156 and 97157. A request for 104 units of 97156 plus 24 units of 97157 GT appears on the authorization as ABH: 128 units. A register built one code per row will not match the letter.
The columns an authorization register needs
A register is a spreadsheet, one row per authorization per code, sorted by end date. Nothing about it needs new software. It needs one owner and a weekly pass, because the numbers that matter change every time a claim is filed.
- Client name, payer, plan, and the authorization number exactly as the letter prints it
- CPT code, plus the authorization class when the payer approves by class
- Units approved, units billed to date, units still available
- Authorization start date, end date, and the date the next request is due
- Place of service and modifiers, because a place-of-service mismatch denies a service the payer already approved
- Rendering provider, and whether that provider is credentialed with this payer
- The trigger date, set as a calendar task rather than a note in the chart
Two columns get skipped, and both cost money. Modifiers change what can be billed together: in Maryland, 97156 with modifier U2 means the client was present and cannot be billed concurrently with 97153, while 97156 without U2 can be. The rendering provider column matters because the credential has to be in place before the claim goes out. Credentialing that lags behind hiring is one way an authorized service becomes an unbillable one.
Units billed has to come from the claim file, not the schedule. The 837 claim and the 835 remittance are the only record of what was actually billed, and a canceled, undocumented or unbilled session does not consume units. Registers built from the appointment calendar drift, usually toward showing fewer units left than the payer’s own balance.
One owner, one weekly pass. The register gets read in the same huddle that reviews the schedule, and it produces its own task list: every authorization inside 45 days of its end date, and every case past 75 percent consumption, with a named owner and a date attached. Renewal packets start from those two lists instead of from a clinician remembering a letter that arrived in March.
Consumption runs off the schedule, not the authorization
The payer approved a weekly intensity and a total. Those two numbers agree only when the schedule is delivered exactly as written, which is not how ABA weeks run. Burn rate is simple arithmetic once the conversion is fixed: weekly hours multiplied by four gives units a week.
| Hours approved per week | Units per week | Units across a 180-day authorization |
|---|---|---|
| 10 | 40 | 1,029 |
| 15 | 60 | 1,543 |
| 20 | 80 | 2,057 |
| 25 | 100 | 2,571 |
| 30 | 120 | 3,086 |
Read that table as a warning rather than a plan. A 20-hour authorization executed at 22 hours a week spends 88 units a week, so the 2,057 units are gone in about 23 weeks, roughly 16 days before the authorization itself ends. Unless the payer backdates the next approval, those sessions fall outside coverage. Carelon Maryland backdates ABA authorizations by up to 20 calendar days, and not every payer allows it at all.
Where the extra units go
- Make-up sessions added after cancellations, which spend units on a schedule nobody priced
- A second rendering provider on the same day, when the payer counts units across all providers
- Supervision, caregiver training and group codes that share an authorization class with treatment codes
- A start date that moved, so the same unit total stretches across more weeks than planned
- School breaks and holidays, which reduce delivered units and leave the authorization part-used
The last item cuts both ways. A case running at half the approved rate never trips a unit threshold, so a practice watching only for a ceiling of units will still hit a wall on the end date.
Two triggers, and you use the earlier one
The date is the trigger most teams use, and they set it too late. Federal rules now fix the outside decision time for Medicare Advantage, Medicaid fee-for-service, Medicaid managed care and CHIP managed care plans at 7 calendar days for a standard request and 72 hours for an expedited one, with the operational provisions starting January 1, 2026. That is a ceiling on the payer. A request pended for missing documentation extends the practical timeline, so the working lead time is longer than the rule.
Two triggers belong in the register. The unit trigger fires at 75 to 80 percent consumed. The date trigger fires 30 to 45 days before the end date. Whichever fires first starts the packet. The unit trigger catches fast consumption, and the date trigger catches a case that never comes close to the ceiling.
Sort the register by end date, then by percent consumed, and check that every case inside 45 days has a clinician assigned to the reassessment. A reassessment booked into the last two weeks of an authorization is the usual reason a packet misses its window.
Maryland’s ABA program requires progress data no more than 30 days old at the time of the request, and the observation behind a reassessment has to fall inside the same window. A packet assembled in the final ten days carries data the payer’s own standard calls stale.
The reauthorization packet, assembled from the register
Print the register row: units approved, units billed, units left, end date. If authorized hours went unused, address that in the plan instead of asking for more. Maryland’s reviewer expects the current authorized hours to be in use before an increase is requested.
Progress data and the observation have to sit within 30 days of the request. As of April 1, 2026, Maryland requires graphs for every goal in a reassessment report, each stating the data collection method and the mastery criteria.
Measurable goals, baseline data, treatment intensity, caregiver goals, generalization, fading and discharge criteria. Use the payer’s template when one exists, and attach the assessment rather than pointing at it.
State total units per code, the place of service and the modifiers. Confirm the portal accepted the same numbers the treatment plan states, because reviewers compare the two forms.
Record the received date. Maryland times its 7-day turnaround from receipt, and requests sent by email or fax are dated on arrival rather than on the day they were prepared.
No billable session before the start date and none after the end date. When a gap is unavoidable, keep the documentation complete so the next authorization can be backdated where the payer allows it.
Where untracked units end up
Two federal documents published in 2026 explain why payers now read unit data more closely than they did three years ago.
The HHS Office of Inspector General audited Colorado’s fee-for-service Medicaid payments for ABA in 2022 and 2023 and estimated at least $77.8 million in improper payments, with another $207.4 million flagged as potentially improper. Every one of the 100 sampled enrollee-months contained at least one improper or potentially improper claim line. One facility was paid for 799 units of 97153 in a single month while the session notes supported 195 units, a difference of 604 units, or 151 hours. The report recommended that Colorado refund $42.6 million in federal share and begin a statewide postpayment review.
CMS published a 173-page ABA toolkit for state Medicaid and CHIP programs in August 2026. It creates no new federal requirement, and it tells states which patterns to hunt for: overlapping treatment, excessive service hours, reevaluations that do not reflect progress, and plans with no sign of caregiver involvement. The spending figures show why the attention is there. Between 2021 and 2025, spending on ABA for children with an autism diagnosis in Medicaid and CHIP rose 421 percent while the number of children receiving services rose 189 percent. The toolkit points states toward prior authorization before treatment, concurrent review during it, and reauthorization near the end of the approved period.
Little of that lands on the clinical team when the register is honest. Session notes with start and stop times, an electronic visit verification record where the state requires one, and the authorization letter filed with the case answer the first questions an auditor asks. Unit tracking is the control that gives the earliest warning, and it is the part of behavioral health revenue cycle management a practice can run without new software.
Questions about tracking ABA authorizations
Multiply the approved weekly hours by four to get units a week, then multiply by the weeks in the authorization period. A 20-hour week is 80 units, and across a 180-day authorization that comes to about 2,057 units. Compare that figure with the hours the schedule actually books, because make-up sessions and second providers consume units faster than the approval assumed.
Set two triggers and act on whichever fires first: units consumed reaching 75 to 80 percent, or 45 days before the end date. The date trigger has to leave room to rebuild the clinical data, since programs such as Maryland Medicaid require progress data and the reassessment observation to be no more than 30 days old at submission.
Sessions delivered without a valid authorization are unbillable unless the payer backdates the new approval. Carelon Maryland allows backdating up to 20 calendar days, and some payers allow none. The safer sequence is to submit early enough that the new start date lands on or before the old end date, and to hold sessions only while an authorization is in force.
Not always. Some payers authorize by class, grouping related codes under one unit total. Carelon Maryland groups 97156 and 97157 under a single class, so a request for 104 units of 97156 plus 24 units of 97157 appears as 128 units. When a register expects a per-code balance and the payer keeps a per-class balance, one code runs out early and another late.
Because the register counts the authorization while the schedule counts the week. Make-up sessions, a second rendering provider, or a delivery rate above the approved weekly hours spend units faster than planned. A 20-hour approval executed at 22 hours a week runs out roughly 16 days early. Cancellations do the opposite and leave units unused at expiration.
An updated treatment plan on the payer’s template, current progress data with graphs for each goal, the reassessment observation, the diagnostic evaluation or referral where the payer requires one, and the unit request stated by code with place of service and modifiers. Maryland has required the goal graphs since April 1, 2026 and times its review from the date the packet arrives.
Under federal rules that began applying in January 2026, Medicare Advantage, Medicaid fee-for-service, Medicaid managed care and CHIP managed care plans must decide standard requests within 7 calendar days and expedited requests within 72 hours. A request pended for missing documentation extends the practical timeline, so reauthorization cycles in practice run longer than the rule.
The bottom line
An authorization that runs out of units before it runs out of dates is a denial with a delay built into it, and the practice usually learns about it from the remittance. Keep units approved, units billed and days remaining in one place, and set the trigger where the packet can still be built from data the payer will accept. If nobody can say how many ABA units are left on each open authorization today, a revenue cycle review is the place to start.
How many ABA units are left on each open authorization?
We work ABA and behavioral health claims end to end: authorization registers, unit tracking, reauthorization packets and the denials that follow a coverage gap. Send us one month of claims and we will show you where authorized units went unbilled.
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