Last reviewed: October 2026
In most healthcare organizations, conversations about billing rarely start with “revenue cycle optimization.” They start with something simpler: why payments are taking longer than expected, or why certain claims are still sitting unpaid weeks after they were sent. At Prospect Healthcare Solutions, this is often where discussions begin, and in most cases everything leads back to one area: AR in medical billing.
AR rarely shows itself loudly. It builds quietly through pending claims, follow-ups that didn’t happen on time and denials that were never fully worked. This guide explains what AR is, how to measure it with days in AR and aging buckets, and how to keep it under control.
What Is AR in Medical Billing?
AR (accounts receivable) in medical billing is the money a practice is still owed for services it has already provided. It includes claims waiting on insurance payers and balances patients still owe after insurance pays. Every visit becomes AR the moment it’s billed, and stays AR until it’s paid, adjusted or written off.
AR isn’t a static report. It’s an active process: every open claim either moves toward payment or ages, and the longer a balance sits, the less likely it is to be collected.
How AR Builds Up in Real Billing Workflows
No one notices AR on day one. A claim goes out and everything feels normal. Then time passes. The claim enters payer review and is paid, denied or delayed, and someone has to follow up, often more than once, until it’s resolved.
In real settings, this is where things slow down. Not because people aren’t working, but because claim volume grows faster than follow-up capacity. That gap is where AR grows.
Days in AR: The Formula and a Worked Example
Days in AR shows how long, on average, it takes to turn a charge into payment. It’s the single number most practices use to judge billing performance.
Days in AR = Total AR ÷ Average daily charges
Average daily charges are your gross charges over a period divided by the number of days in it. Most practices use the last 90 days.
| Step | Example |
|---|---|
| 1. Gross charges, last 90 days | $720,000 |
| 2. Average daily charges | $720,000 ÷ 90 = $8,000 |
| 3. Total AR today | $240,000 |
| 4. Days in AR | $240,000 ÷ $8,000 = 30 days |
If the same practice’s AR grew to $440,000 with the same charges, days in AR would be 55. Nothing about patient volume changed; claims are simply taking longer to turn into cash.
Many practices aim for days in AR of 30 to 40, and treat anything above 50 as a sign of collection delays. Specialty, payer mix and the share of patient balances all move this number, so the trend over time matters more than any single month.
AR Aging Buckets
Days in AR gives one average. An AR aging report shows where the money actually sits, grouped by how long each balance has been open:
| Aging bucket | What it usually means | What to do |
|---|---|---|
| 0–30 days | Normal processing time for most payers | Check that claims were accepted; fix rejections right away |
| 31–60 days | Some claims should have paid by now | Check claim status and work any denials |
| 61–90 days | Something is wrong with the claim or payer | Call or use the payer portal; correct and resubmit |
| 91–120 days | High risk; timely filing and appeal deadlines are getting close | Escalate, appeal and document every contact |
| 120+ days | Hardest to collect | Final appeals, patient collections or write-off review |
A healthy AR has most of its balance in the first two buckets. If the share over 90 days keeps rising, follow-up isn’t keeping up. For running and reading the report, see our guide to aging in medical billing.
The AR Follow-Up Process
Inside billing operations, AR work is continuous tracking, not a single task. A typical follow-up cycle:
- Prioritize. Work the oldest and highest-value claims first, and anything close to a timely filing deadline.
- Check status. Use the payer portal, an electronic claim status inquiry (276/277) or a call.
- Find the reason. Missing information, a denial, a coding issue or a payer delay.
- Fix and resubmit, or appeal with supporting documentation.
- Record it. Note what was done and set the next follow-up date.
- Move patient balances to statements once insurance has paid its share.
Denials and AR
Denials are one of the biggest reasons AR ages: every denied claim sits in AR until it’s corrected or appealed. Start with why the claim was denied, fix it and resubmit, then track denial patterns so the same error doesn’t repeat. For denial codes, appeal steps and prevention, see our complete guide to AR denial management.
Medical Billing AR Management Best Practices
There’s rarely a single fix. Improvements come from small, consistent habits:
- Review the aging report every week, not once a month.
- Start follow-up early; the first weeks after submission matter most.
- Keep payer follow-up structured, with a fixed rhythm instead of random checks.
- Submit clean claims: verify eligibility and authorizations before the visit.
- Track denial reasons by payer and fix the cause upstream.
- Watch days in AR and the share over 90 days as a trend, month to month.
Why AR Management Often Fails Before It Becomes Visible
AR rarely becomes a problem overnight. A claim might look fine at submission, but small issues like missing details, a delayed follow-up or a payer-specific requirement slowly turn it into part of a larger aging pattern. By the time it shows clearly in reports, the backlog has already formed.
That’s why AR problems are usually gradual gaps in attention, not sudden failures. Treating AR as a workflow discipline that starts at registration, rather than a report to read at month-end, is what keeps it under control.
AR vs AP in Healthcare
AR and AP sometimes get mixed up when financial reports are reviewed quickly:
| Accounts receivable (AR) | Accounts payable (AP) | |
|---|---|---|
| What it is | Money owed to the practice | Money the practice owes |
| Who owes it | Insurance payers and patients | Owed to suppliers, vendors and service providers |
| Examples | Unpaid claims, patient balances | Medical supplies, software, rent |
| Goal | Collect faster | Pay on time, on agreed terms |
Need Help Bringing AR Down?
When follow-up can’t keep up with claim volume, AR grows no matter how hard the team works. Our accounts receivable services take over insurance follow-up, denial resolution and aging AR recovery, with reporting on days in AR and aging by payer.
FAQs
What is AR in medical billing?
The money a practice is still owed for services already provided: claims waiting on insurance and balances patients still owe.
How do you calculate days in AR?
Divide total AR by average daily charges. Average daily charges are gross charges over a period (usually 90 days) divided by the number of days.
What is a good days in AR number?
Many practices aim for 30 to 40 days and treat anything above 50 as a sign of collection delays. Specialty and payer mix change what’s realistic.
What are AR aging buckets?
Groups of open balances by age: 0–30, 31–60, 61–90, 91–120 and over 120 days. The older the bucket, the harder the balance is to collect.
Why does AR increase in healthcare billing?
Common reasons are claim denials, delayed follow-up, incomplete or incorrect claims, and missing eligibility or authorization checks.
What is the difference between AR and AP?
AR is money owed to the practice by payers and patients. AP is money the practice owes to suppliers and vendors.