Days in A/R: what the number means and what good looks like

Days in accounts receivable is the most quoted number in medical billing. It is also the one most often calculated in a way that flatters whoever is reporting it.

The standard formula

Days in A/R is total accounts receivable divided by average daily charges:

Days in A/R  =  Total A/R  ÷  (Total charges over a period ÷ days in period)

A practice with $300,000 outstanding and $10,000 of average daily charges sits at 30 days.

That much is uncontroversial. Everything after it is where the number gets soft.

Three decisions that change the answer

Which charges. Using a 90-day lookback smooths seasonality. Using a 30-day lookback makes a strong recent month pull the number down. Neither is wrong, but comparing a 30-day calculation to a 90-day benchmark is meaningless, and that comparison happens constantly.

Which receivables. Some reports exclude credit balances. Some exclude patient responsibility. Some exclude anything already written off — which is the significant one, because a biller who writes off aged claims aggressively will show an excellent days-in-A/R figure while collecting less money.

Gross or net. Gross charges are what you billed. Net is what you can realistically expect after contractual adjustments. A days-in-A/R built on gross charges will read lower than one built on net, because the denominator is inflated.

A number reported without these three stated is not comparable to anything.

What good looks like

For most outpatient specialties:

Specialties with heavy prior-authorisation burden or significant workers' compensation volume run legitimately higher, and should be judged against their own baseline rather than a general figure.

The number that matters more

Days in A/R is an average, and averages hide the thing you need to see. A practice at 32 days can be in better or worse shape than one at 38 depending entirely on distribution.

Percentage of A/R over 90 days is the better signal. Under 10% is healthy. Above 20% means a meaningful share of your receivables is approaching the point where it stops being collectible at all.

A practice can lower its average by collecting quickly from easy payers while a growing tail of hard claims ages quietly underneath. The average improves. The position worsens.

What actually moves it

In order of effect:

1. Submit faster. Days between service and submission are pure, free delay. A practice filing at day 5 has given away five days before a payer has seen anything.
2. Reduce denials. A denied claim restarts the clock, and a denial worked at day 45 lands as payment around day 75.
3. Work the tail deliberately. Receivables over 90 days need different handling from current ones — by payer, by reason, by age bucket.
4. Verify eligibility twice. Front-end accuracy shows up in A/R weeks later, which is why the connection is so often missed.

If a billing company reports its days in A/R without saying which charges, which receivables, and gross or net, ask. The answer tells you more than the number does.