Will this be paid?

Bundling, unit ceilings, add-on rules, site of service, medical necessity and who may assist — answered against your codes.

The claim — extensive sinus and nasal surgery

Line	Code	Procedure	Allowable
L1	31256-50	Exploration, maxillary sinus — bilateralendoscopic family	$158.8
L2	31254-RT	Nasal/sinus endoscopy, partial ethmoidectomy — rightendoscopic family	$214.07
L3	30520-	Repair of nasal septum	$625.29

Nothing on this claim denies. Every line is payable and every modifier is used correctly. The only question is what it should pay — and four rules apply to it in an order that changes the answer. The endoscopic family's diagnostic base code is 31231 at $56.23.

Compare against

Correct adjudication

Correct

Bundling, then bilateral, then EMPR within the family, then MSR between groups. Each rule sees the output of the one before it.

1Resolve bundling
Nothing bundles here. There is no procedure-to-procedure edit between any pair on this claim, so no modifier is needed and none would help — a distinct-service modifier on a pair that carries no edit is inert. Every line stays payable, which is where the interesting part starts.
- L1no PTP pair — payable$158.8
- L2no PTP pair — payable$214.07
- L3no PTP pair — payable$625.29
2Resolve bilateral value
Modifier 50 pays one line at 150% — but only where the code's bilateral indicator allows it. 31256 is indicator 1, so it does. 30520 is indicator 0, so appending 50 to it buys nothing. This resolves BEFORE any reduction, because every later rule ranks against the value of the service actually performed.
- L1$158.8 × 1.5$238.2
- L2unilateral (RT) — no bilateral uplift$214.07
- L3bilateral indicator 0 — no 150% adjustment$625.29
3Resolve endoscopic multiple-procedure reduction
Endoscopies in one family are grouped. The highest-valued pays in full; every other line in the family subtracts the family's diagnostic base code (31231, $56.23). It is a subtraction, not a percentage — that distinction is what scenario B gets wrong.
- L1highest in family — pays 100%$238.2
- L2$214.07 − $56.23 base$157.84
- familyendoscopic family total$396.04
4Resolve standard multiple-surgery reduction
The endoscopic family's total is now one service, ranked against the non-endoscopic procedure. The higher pays 100%; the lower takes the standard 50%. Here the septoplasty outranks the family, so the family is cut — and the cut lands on each line in it. The base-code subtraction and the 50% are not alternatives: one is the reduction inside the family, the other is the reduction between the family and everything else on the claim.
- L3ranks first — pays 100%$625.29
- familyendoscopic family total $396.04 × 50%$198.02
- L1$238.20 × 50%$119.1
- L2$157.84 × 50%$78.92

Total $823.31

RT/LT split on an endoscopic code

Overpaid $11.59

The provider bills the bilateral endoscopy as two lines, 31256-RT and 31256-LT, instead of one line with modifier 50.

1Two lines, same code, opposite sides
The engine never merges RT and LT of the same code into one bilateral unit, so the bilateral indicator is never enforced.
- L1a31256-RT — treated as a standalone endoscopy$158.8
- L1b31256-LT — treated as a standalone endoscopy$158.8
2EMPR runs against two lines instead of one
Having two endoscopies where there should be one bilateral service, the second takes the base-code subtraction as though it were a different procedure.
- L1ahighest in family — pays 100%$158.8
- L1b$158.8 − $56.23 base$102.57
- codepaid for 31256$261.37
Where it breaks — $261.37 for a service worth $238.2 as a bilateral line. Splitting a bilateral procedure across two lines pays MORE than billing it correctly, which is the wrong incentive to leave in an engine.
3The inflated family is ranked and cut
The family now totals more than it should, but it still ranks second against the septoplasty and takes the 50% group cut. The cut halves the overpayment; it does not remove it.
- family$261.37 + $157.84$419.21
- L1$261.37 × 50%$130.69
- L2$157.84 × 50%$78.92

Total $834.9

Correct

$823.31

Scenario A

$834.9

Difference

+$11.59

paid above the correct amount

Line	Correct	Scenario A	Difference
L1 31256	$119.1	$130.69	+$11.59
L2 31254	$78.92	$78.92	—
L3 30520	$625.29	$625.29	—

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