If more than 15% to 20% of your total accounts receivable is sitting over 90 days old, your clinic has a collections problem worth investigating. Some AR over 90 days is normal. A rising percentage, month over month, usually points to slow claim submission, weak payer follow-up, or a denial rate that nobody is tracking closely enough.
What “AR over 90 days” actually means
Accounts receivable, or AR, is money owed to your practice for services you already delivered. It sits on your books until a payer or a patient pays it, adjusts it, or you write it off.
Practices track AR in aging buckets: current to 30 days, 31 to 60, 61 to 90, and over 90 days (some break the last bucket into 91 to 120 and 120-plus). The older a claim gets, the harder it becomes to collect. Documentation gets harder to reconstruct, and timely filing windows start closing with some payers.
“AR over 90 days” is the percentage of your total outstanding receivables that falls into that oldest bucket. It’s one of the clearest signals of how well your billing process is actually working, not how busy your schedule looks.
What is the benchmark
Here is where you need to be careful with numbers you find online, because sources disagree, and a lot of what shows up in search results comes from billing vendors quoting each other.
The range that shows up consistently across named industry sources: keeping AR over 90 days under roughly 15% to 20% of total receivables is a reasonable target for a primary care or specialty practice. Becker’s Hospital Review, a healthcare finance trade publication, states the figure should stay below 20%. Some RCM guidance sets a tighter bar, closer to 10%, for high-performing practices. The Medical Group Management Association (MGMA), which runs the industry’s most widely cited benchmarking survey, tracks the related 120-plus day bucket separately in its DataDive Better Performers reports and finds that top-performing practices consistently carry a meaningfully smaller share of AR in that oldest bucket than the average practice, though the exact percentage varies by specialty and by year.
The honest answer: there is no single number that applies to every clinic. A chiropractic practice with a clean, mostly commercial payer mix should be able to run tighter than a small clinic carrying a heavy Medi-Cal managed care caseload, where plans like CalOptima, IEHP, or L.A. Care can take longer to adjudicate and where prior authorization delays push claims into an older bucket before they’re even submitted. Use 15% to 20% as your general ceiling, and watch the trend line more than the single snapshot.
Why small California clinics run higher than the benchmark
A few patterns show up again and again in small CA practices:
Payer mix. Clinics with a larger share of Medi-Cal managed care patients tend to see longer adjudication timelines than clinics billing mostly commercial payers. That’s a structural reality of the program, not a sign your billing team is failing.
Denials that never get worked. A denied claim doesn’t disappear. It sits in AR, aging, until someone appeals it, corrects it, and resubmits it. If your practice doesn’t have a dedicated denial workflow, denied claims are often the biggest single driver of your over-90 bucket.
Credentialing gaps. If a provider isn’t fully credentialed or enrolled with a payer at the time of service, claims can sit unpaid for months while the issue gets sorted out. This shows up constantly in small clinics adding a new provider without confirming enrollment first.
Slow initial follow-up. Claims that don’t get a first follow-up call or portal check within 30 days of submission are far more likely to still be unpaid at 90 days. Momentum matters here. The longer a claim sits untouched, the older it gets before anyone notices.
Legitimate exceptions. Some claim types normally take longer than 90 days to resolve: workers’ compensation, personal injury claims, and certain out-of-network claims. If those make up part of your payer mix, expect your over-90 percentage to run a bit higher than a clinic without them, and factor that into how you read your own number.
How to calculate your own percentage
Pull your AR aging report from your practice management system or clearinghouse. Divide the dollar amount in the over-90-day bucket by your total outstanding AR, then multiply by 100.
Total AR over 90 days ÷ Total AR (all buckets) × 100 = your percentage
Run this monthly, not quarterly. A number that looks fine in a snapshot can hide a trend that’s been climbing for months.
If you want to see where your practice stands without pulling a full report, CNB’s claims calculator gives you a quick way to estimate what your AR aging is costing you in delayed cash flow.
What to do if your number is too high
Start by pulling the aging report and sorting the over-90 bucket by payer. You’ll usually find the problem concentrated in two or three payers, not spread evenly across all of them. From there:
Work the oldest claims first, since they’re closest to falling outside timely filing or appeal windows. Confirm which of those claims are sitting on a denial you haven’t appealed yet. Check whether any providers involved have a credentialing or enrollment gap with the payer in question. Then build a standing follow-up cadence so new claims don’t get the chance to age into that bucket in the first place.
This is the exact workflow CNB runs for small-to-medium California clinics: claim follow-up on a set schedule, denial management that actually works the appeal instead of writing it off, and credentialing kept current so claims don’t stall before they’re even reviewed. If your AR over 90 has been climbing and you want a second set of eyes on it, start with a free billing audit or see how CNB approaches small clinic billing.