A contractual allowance adjustment explains why an insurance payment is lower than the amount you billed. When teams post it wrong, however, patient balances become inaccurate, A/R looks inflated, and real underpayments slip through.
In this guide, we explain what the adjustment is, how to calculate it, how Medicare handles it, and how to post it correctly on every remittance.
What Is a Contractual Allowance Adjustment?
A contractual allowance adjustment is the difference between your billed charge and the amount the payer allows under your contract or fee schedule. Then, after adjudication, you write it off, which reduces A/R to the allowed amount.
For example, if you bill $250 and the contracted rate is $180, the $70 difference is the contractual allowance adjustment. Importantly, it is neither a patient balance nor a billing error. In-network providers generally cannot bill it to the patient.
How to Calculate a Contractual Allowance Adjustment
Overall, the formula is simple. First, take your billed charge. Then, subtract the payer’s allowed amount. Finally, the result is the adjustment.
Quick visual guide
From billed charge to patient balance
Billed charge
Your standard fee, for example $300.
Allowed amount
What the contract allows, for example $220.
Contractual adjustment
Billed minus allowed: $80, written off.
Patient share
Any deductible, copay, or coinsurance within the $220.
Contractual allowance adjustment = billed charge − allowed amount
| Setting | Billed charge | Allowed amount | Adjustment |
|---|---|---|---|
| Primary care visit | $180 | $140 | $40 |
| Hospital outpatient procedure | $1,200 | $900 | $300 |
| Physical therapy session | $150 | $115 | $35 |
| Psychotherapy session | $220 | $170 | $50 |
| Medicare office visit | $280 | $200 | $80 |
However, note that these amounts are illustrations only. Actual allowed amounts depend on your contracts, locality, and the year’s fee schedule.
Where It Fits in the Revenue Cycle
In fact, every step before posting affects the final number. First, staff verify eligibility, network status, and benefits. Next, coders assign CPT, HCPCS, and ICD-10-CM codes, and the claim goes out. Then, the payer adjudicates the claim and sets the allowed amount.
After that, the ERA or EOB arrives, and the billing team posts the payment, the adjustment, and the patient share. Typically, the adjustment appears as CO-45, which means the charge exceeds the fee schedule or contracted amount. Finally, any deductible, copay, or coinsurance becomes the patient balance. To read these remittances with confidence, see our guide to the EOB in medical billing.
How Does Medicare Handle Contractual Adjustments?
Unlike many commercial plans, Medicare pays set rates rather than billed charges. For physician services, the allowed amount comes from the Medicare Physician Fee Schedule (MPFS). Specifically, CMS sets it using relative value units, geographic adjustments, and an annual conversion factor. You can check any code in the CMS PFS look-up tool.
So, if your charge exceeds the allowed amount, the difference is the Medicare contractual adjustment. Moreover, participating providers cannot bill beneficiaries for it beyond the deductible and coinsurance. Notably, Medicare’s 2% sequestration cut is a separate adjustment, so post it on its own line.
Contractual Allowance vs. Contractual Adjustment
Admittedly, many people use these terms the same way. Still, accounting teams often separate them.
| Feature | Contractual allowance | Contractual adjustment |
|---|---|---|
| Meaning | Expected reduction under payer contracts | Actual reduction after adjudication |
| Timing | Forecasting and financial reporting | Payment posting |
| Where it appears | Financial statements | Billing system and patient ledger |
Contractual Adjustments vs. Other Write-Offs
Basically, a contractual adjustment is a required write-off under a payer agreement. In contrast, bad debt, small-balance, and administrative write-offs are business decisions. Therefore, keep them in separate categories. For more detail, our article on write-offs in medical billing explains each type.
How to Catch Underpayments Hidden in Adjustments
Still, here is the risk: if the payer allows less than your contract rate, the extra reduction can hide inside the contractual adjustment. As a result, staff often write off money the practice is owed.
- First, load contracted rates into your billing system
- Next, compare each allowed amount with the expected rate
- Then flag any variance before you post the write-off
- Also, track underpayments by payer and code
- Finally, appeal patterns, not just single claims
Our payment posting services compare every allowed amount against your contracts, so underpayments get caught instead of written off.
Get Contractual Adjustments Posted Right
In short, a contractual allowance adjustment is a normal part of every insured claim. Yet posting it carelessly hides underpayments and distorts A/R. With accurate contract rates and careful posting, your reports stay clean and your revenue stays whole.
Fortunately, Dr Biller RCM helps practices post, reconcile, and recover with end-to-end medical billing services. Request a free RCM audit to find underpayments in your adjustments.
FAQs
What is a contractual allowance adjustment?
Simply put, it is the difference between your billed charge and the payer’s allowed amount under your contract. You then post it after adjudication.
Is a contractual adjustment a write-off?
Yes. In effect, it is a contractual write-off required by the payer agreement. However, it differs from bad debt or administrative write-offs.
Which code shows a contractual adjustment on an ERA?
Most often, you will see CO-45: the charge exceeds the fee schedule or maximum allowable amount.
Can I bill the patient for the contractual adjustment?
Generally, no. That is because in-network and Medicare participating providers can only collect the deductible, copay, and coinsurance.
