Billing below the allowable: the quiet revenue leak

Yes — undercharging is a real, permanent leak

Charging less than a payer's allowed amount doesn't just leave money on the table once — it resets what you can ever collect for that code with that payer, because most contracts, and Medicare itself, pay the lesser of your billed charge or the contracted allowable. Set your charge below the allowable and the payer simply pays your lower number; the difference was never billed, so there's nothing to appeal or recover later.

This is easy to miss because nothing about it looks like an error on your remittance — no denial, no rejection code, just a payment that quietly matches your own charge instead of the higher number the payer was prepared to pay. The claim processed cleanly; it just processed against the wrong ceiling.

How the lesser-of math actually plays out

Think of your charge and the payer's allowable as two independent numbers that only interact through a single rule: pay whichever is lower. If your charge sits above the allowable, the payer pays the allowable and you never see the excess anyway — that part is normal and expected. The costly version is the reverse: your charge sits below the allowable, and the payer now pays your number instead of the higher one it was prepared to pay.

Because the rule only ever caps you at your own number, there's no offsetting benefit to pricing conservatively — you can't accidentally get paid more than the allowable, so a charge set below it has no upside and one very specific downside, repeated on every claim for that code.

Where the allowable actually comes from

For Medicare, the allowable is the RVU-based fee schedule amount CMS publishes and updates annually 1Ref 1Centers for Medicare & Medicaid Services (2026).Physician Fee Schedule.That the Medicare Physician Fee Schedule's RVU-based allowable is published and updated annually through CMS rulemaking., available for any code through the same public search tool you'd use to build a rate comparison 2Ref 2Centers for Medicare & Medicaid Services (2026).Physician Fee Schedule Search.The public lookup tool used to find the current allowable for a code to compare against your own charge master.. Commercial allowables are contract-specific and usually confidential by default, which is exactly why a stale or guessed charge is so easy to leave underpriced without ever noticing.

Run the MPFS lookup for your top codes and compare the result against your own charge master line by line — and remember that GPCIs and localities mean the correct comparison number is your specific locality's rate, not the national average, since a charge that clears the national figure can still sit below your own locality's higher one.

The Medicare-specific trap: ABNs and self-pay defaults

When a Medicare patient owes you directly for a non-covered service, the Advance Beneficiary Notice you issue sets the estimate the patient agreed to pay — and an artificially low estimate on that notice becomes close to a ceiling on what you can collect for that visit, not a starting point you can revise upward after the fact 3Ref 3Centers for Medicare & Medicaid Services (2026).Beneficiary Notices Initiative (BNI).That the Advance Beneficiary Notice sets the collectible estimate for a non-covered service billed directly to a Medicare patient.. Undercharging here is harder to fix retroactively than a routine contracted-payer underpayment.

The practical fix is the same discipline as the rest of your fee schedule: price the ABN estimate against what you'd actually charge a self-pay patient for that service, not a discounted guess offered in the moment to soften the conversation.

Coordination of benefits: the two-payer version

When a patient has both a primary and secondary payer, coordination of benefits determines which one pays first and how much of the remaining balance the second one covers 4Ref 4Centers for Medicare & Medicaid Services (2026).Coordination of Benefits and Recovery Overview.That coordination of benefits determines primary/secondary payer order and how much of the remaining balance a secondary payer covers, based on the billed charge. — and that remaining balance is calculated from your charge, not an abstract full price. A charge set low shrinks what the secondary payer can ever contribute too, so the underpricing loss compounds across both payers on the same claim, not just the primary one.

This is one more reason a single, consistent charge master matters more than it seems: every payer in a coordinated claim is doing math against the same billed number, so one underpriced line item quietly discounts every payer touching that claim at once.

Fixing it: load allowables, don't guess charges

Build your fee schedule from the highest allowable across your actual payer mix for each code, not from a round number that felt reasonable when you opened the practice, and set every charge at or above that ceiling. A charge set even one dollar below the highest allowable in your mix guarantees you're underpaid by exactly that much on every claim for that code, forever, until you change the charge master.

Loading allowables directly into your EHR or billing software, rather than trusting a biller to remember the current numbers, turns this from a periodic audit into a built-in check on every claim you generate.

A one-time cleanup catches the backlog; the ongoing discipline is what keeps it from reappearing. New codes get added to your practice's mix whenever you add a service line, a new payer contract, or a new location, and each of those events is a natural trigger to re-run the comparison rather than waiting for the next scheduled annual review.

Why this compounds beyond billing

An underpriced charge master doesn't stay contained to billing — it understates your practice's real revenue in every downstream calculation that assumes accurate income, from projecting cash flow to deciding when a tax election starts paying for itself. The S-corp math, for instance, already assumes a baseline revenue number; running that calculation against an artificially low one produces an answer that looks less favorable than your practice's real economics support.

The fix compounds the same way the problem does: correcting the charge master once flows through every later calculation that depends on accurate revenue, instead of requiring a separate correction each time you run a new projection.

Treat the annual fee schedule review as a business-planning task, not purely a billing one, and loop in whoever handles your books when you do it. A revenue number that's been quietly understated for years can make a genuinely healthy practice look marginal on paper, which is its own kind of cost even before you count the missed payments themselves.