Net Collection Rate in Medical Billing: Formula, Gross vs Net, and a Worked Example

Net collection rate is payments divided by charges minus contractual adjustments: the share of the money you were entitled to collect that you actually collected. The AAFP calls the same measure the adjusted collection rate; MGMA reports it as the adjusted fee-for-service collection percentage.

Days in A/R measures how fast payments arrive. Net collection rate measures how much collectible money is never collected, and it is the number a practice owner should check first.

Where you see it

Place	What it shows
Billing system collections or payment analysis report	Charges, adjustments and payments for a date-of-service range
MGMA DataDive Cost and Revenue	Adjusted fee-for-service collection percentage, one of three measures MGMA uses to define Better Performers
AAFP practice finance guidance	Adjusted collection rate, with a 95 percent minimum
HFMA MAP Key FM-2	Cash collection as a percentage of net patient service revenue, the hospital version
Billing service contracts	A net collection target as a service level

The formula, gross and net

	Gross collection rate	Net collection rate
Numerator	Payments received	Payments received, net of refunds
Denominator	Total charges	Total charges minus contractual adjustments
What it measures	Mostly your fee schedule; the higher you set charges above the allowed amount, the lower it goes	Collections against the allowed amounts the contracts and fee schedules actually permit
Typical range	Wide, and often 40 to 50 percent for practices that charge well above Medicare	The AAFP cites 95 to 99 percent as average, with 95 as the minimum
Useful for	Spotting fee schedule changes; little else	Judging the billing operation

The AAFP formula in full: payments (net of credits) divided by charges (net of approved contractual agreements) for the selected time frame, times 100, with a 12-month time frame recommended.

The key word is “contractual.” A contractual adjustment is the difference between the charge and the allowed amount, usually CARC 45 on the remittance. A write-off for timely filing, a denial nobody appealed, a bad debt balance or a courtesy discount is not contractual, and it stays in the denominator so the rate reflects it. The most common error is to post those non-contractual losses as contractual. That makes the rate look better, but the money is still lost.

The 90 to 120 day lag

Payments for a date of service arrive weeks or months later: Medicare pays most clean claims within about two weeks, Medicare Advantage and commercial plans take longer, and secondary claims, appeals and patient statements take longer still. Dividing this month’s payments by this month’s charges mixes periods, and the result swings with the volume of charges rather than with collection performance.

The fix is to measure by date of service, not by posting date, and to measure only months in which most claims have been paid or adjusted.

Step	How
Choose a date-of-service window that ended 90 to 120 days ago	For a report run in late October, dates of service through June
Pull charges for that window	Total billed for those dates of service
Pull contractual adjustments and payments tied to those same dates of service	Posted at any time since, including last week
Compute the rate	Payments net of refunds, divided by charges minus contractual adjustments
Report the open balance separately	What is still unpaid for that window; it will move the rate when it resolves

A rolling 12-month window smooths the result and is what the AAFP recommends. A single month, measured at 120 days, is better for finding the month when something went wrong.

What a low rate means

Rate falls because	How to confirm	Common source
Timely filing write-offs	CARC 29 denials and the adjustment code used to write them off	277CA rejections nobody re-sent; late charge entry
Denials written off without appeal	Denial write-off adjustments by CARC	A denial queue that is worked by dollar only, so small lines expire
Bad debt	Patient balances moved to collections or written off	Statements not sent; no estimate or collection at check-in
Underpayments posted as contractual	Compare the posted CARC 45 amount with the contract’s allowed amount by CPT	The shortfall is taken out of the denominator, so the rate does not show it
Credits and unapplied cash	Credit balances and unapplied payments on the A/R	Payments that were never matched to a charge
Secondary balances never billed	Claims with a primary payment and an open balance and no secondary claim	Crossover not set up; patient’s supplemental plan never loaded

Worked example

An illustrative freestanding radiation oncology center measures dates of service January through March, with the report run in July.

Input	Amount
Charges, dates of service January 1 to March 31	1,200,000.00
Contractual adjustments posted against those dates	690,000.00
Payments posted against those dates	475,000.00
Refunds issued against those dates	5,000.00
Still open on those dates	6,000.00

Net collection rate: (475,000.00 minus 5,000.00) divided by (1,200,000.00 minus 690,000.00) equals 470,000.00 divided by 510,000.00, or 92.2 percent. Gross collection rate: 475,000.00 divided by 1,200,000.00, or 39.6 percent.

The 40,000.00 gap between 510,000.00 collectible and 470,000.00 collected breaks down to 14,000.00 of timely filing write-offs on 77427 and 77387-26 lines that were rejected in February and never re-sent, 11,000.00 of patient balances sent to bad debt, 9,000.00 of 77412 lines downgraded to 77407 and never appealed, and 6,000.00 still open. The first and third items are 23,000.00 of money the contracts allowed.

Now the most common error. Suppose the 9,000.00 of downgrades had been posted as contractual adjustments, because the remittance carried CARC 45 and nobody compared it with the contract. Contractual adjustments become 699,000.00, the denominator becomes 501,000.00, and the rate reads 470,000.00 divided by 501,000.00, or 93.8 percent. The rate is 1.6 points higher, but the practice has still lost the same 9,000.00.

What to do

• Post adjustments with distinct codes: contractual, timely filing, denial write-off, bad debt, courtesy. The rate is only accurate if the adjustment codes are.
• Measure by date of service at 90 to 120 days, and keep a rolling 12-month figure beside it.
• Compare CARC 45 amounts with the contract allowed amount for the ten highest-volume codes each quarter; in radiation oncology that is 77402, 77407, 77412, 77387-26, 77427, 77301, 77336 and the simulation codes.
• Read the rate by payer. One plan at 85 percent while the rest sit at 96 points to a contract or payer problem with that one plan.
• Iridium Suite’s reporting shows billed, allowed and paid by CPT code and payer, which is where an underpayment posted as contractual first becomes visible.

Related terms

• Allowed amount
• Days in A/R
• Claim denial rate
• Clean claim rate
• Timely filing limits
• Group codes and reason codes on a remittance

Further reading: AAFP: Managing practice finances (adjusted collection rate); MGMA: Data mine, predicting bad debt with key revenue cycle metrics; HFMA MAP Keys, 2023 edition (PDF), FM-2; X12: Claim Adjustment Reason Codes.