Bilateral surgery indicator 1 means 150 percent, not 200.

What the indicator is

The Medicare Physician Fee Schedule payment policy indicator file carries a field called Bilateral Surgery Indicator (Modifier 50), at position 36 of the record (Chapter 23, section 50.6). Chapter 12 calls the same field Field 22 of the Medicare Fee Schedule Data Base. It tells the claims system whether the bilateral payment rule applies to a code. Only the value 1 triggers the 150 percent adjustment.

The five values

• 0: the 150 percent adjustment does not apply, either because of physiology or anatomy, or because the code is described as unilateral and a separate bilateral code exists.
• 1: the adjustment applies. Medicare pays the lower of the total actual charge for both sides or 150 percent of the fee schedule amount for a single code.
• 2: no adjustment, because the relative values are already based on a bilateral procedure (the descriptor says bilateral, says unilateral or bilateral, or the procedure is usually done on both sides).
• 3: the usual adjustment does not apply; these are generally radiology or other diagnostic tests. With modifier 50, base payment on the lesser of the charges for each side or 100 percent of the fee schedule amount for each side.
• 9: the concept does not apply.

How to bill it

When a procedure is not described as bilateral, CMS tells physicians to report it with modifier 50 as a single line item, and notes that this differs from the CPT coding guidelines, which call for two lines (Chapter 12, section 40.7). If the descriptor already says bilateral, or unilateral or bilateral, do not add modifier 50. Claims systems also recognize the same code on two lines, once with LT and once with RT, as a bilateral surgery. Some codes with indicator 0 can legitimately be done more than once on one day and should not carry modifier 50; the contractor then prices them under the multiple surgery rules.

Bilateral and multiple procedures together

If a bilateral surgery is billed with other procedures on the same day, the bilateral adjustment is applied first. The 150 percent amount is treated as one payment amount, ranked with the other procedures, and then the multiple procedure reductions are applied (Chapter 23, section 50.6; Chapter 12, section 40.6.C). See the multiple procedure indicator page.

Worked example (hypothetical numbers)

Suppose the fee schedule amount for one side is $1,000 and the code has indicator 1. If the practice charges $1,800 for both sides, the cap is $1,500 and Medicare allows $1,500. If it charges $1,200 for both sides, the lower figure applies and the allowed amount is $1,200. With indicator 3 and the same $1,000, each side is capped at $1,000 and paid on the lesser of its own charge, so two sides can reach $2,000. The calculator above reproduces this on your numbers.

Where the row wording needed correcting

The search phrase pairs indicator 1 with a "150 percent rule". CMS applies 150 percent only to indicator 1. Indicators 0, 2, 3 and 9 each mean something different, which is why the page lists all five.

FAQ

What does bilateral surgery indicator 1 mean?

The 150 percent payment adjustment for bilateral procedures applies. Medicare pays the lower of the total actual charge for both sides or 150 percent of the fee schedule amount for a single code.

Does indicator 2 also pay 150 percent?

No. Indicator 2 means the 150 percent adjustment does not apply because the relative values are already based on the procedure being done bilaterally.

Is modifier 50 billed on one line or two?

CMS says to report a bilateral procedure on a single line with modifier 50, and notes this differs from CPT guidance that calls for two lines. Do not add modifier 50 to a code whose descriptor already says bilateral.

What happens when a bilateral surgery is billed with another procedure?

The bilateral adjustment is applied first. The 150 percent amount counts as one payment amount, which is ranked with the other procedures before the multiple procedure reductions apply.

What does indicator 3 mean?

The usual bilateral adjustment does not apply. These are generally radiology or other diagnostic tests, paid on the lesser of the charges for each side or 100 percent of the fee schedule amount for each side.

Sources

Retrieved 2026-11-02 from the CMS documents below. Indicator meanings are paraphrased from the CMS definitions; no AMA CPT descriptors are reproduced. CMS revises the fee schedule and its manuals, so check the current text.

• CMS: Medicare Claims Processing Manual, Chapter 23, Fee Schedule Administration and Coding Requirements (Rev. 13701, issued 06-16-26): section 50.6, Bilateral Surgery Indicator values 0-3 and 9 (retrieved 2026-11-02).
• CMS: Medicare Claims Processing Manual, Chapter 12, Physicians/Nonphysician Practitioners (Rev. 13753, issued 05-07-26): section 40.7, claims for bilateral surgeries; section 40.6.C item 16 (retrieved 2026-11-02).
• CMS: MLN907166, Global Surgery booklet (December 2025): overview of the national global surgery policy (retrieved 2026-11-02).