Modifier 25 vs 59 (and 51 vs 59, 24 vs 25) for Medicare

Modifier 25 goes on an E/M visit to show it was a significant, separately identifiable service on the same day as a procedure; modifier 59 goes on a procedure or other non-E/M service to show it was distinct from another procedure that an NCCI edit would otherwise bundle. They never go on the same kind of line: CMS says 59 must not be appended to an E/M code, and 25 is only for E/M codes.

Modifier 25 vs 59 at a glance

When to use modifier 25

Medicare pays an E/M on the day of a procedure with a global period when the practitioner shows "the service is for a significant, separately identifiable E/M service that is above and beyond the usual pre- and post-operative work of the procedure" (ch. 12, §30.6.6B). Three things follow from the manual:

• Same practitioner, same patient, same day. 25 is only for an E/M by the same physician or qualified NPP who did the procedure or other service.
• A different diagnosis isn't required. CMS says so directly. What matters is whether the visit went beyond deciding to do the procedure.
• It can't create two E/M visits. Contractors may not use 25 to pay multiple E/M services on the same day by the same physician.

The decision to perform a minor procedure (000 or 010 global days) is always part of the procedure payment. A visit that ends in a joint injection (20610, a 000-day global code), with no other problem addressed, doesn't support 25. A visit that manages the patient's diabetes and hypertension and also includes a joint injection for knee pain does.

If the visit on the day of or the day before a major surgery (090 global days) led to the decision to operate, the modifier is 57, not 25.

When to use modifier 59 and the X modifiers

NCCI procedure-to-procedure (PTP) edits list code pairs that usually shouldn't be billed together. An edit with a correct coding modifier indicator of 0 can never be bypassed; with an indicator of 1, an NCCI-associated modifier can bypass it when the services were genuinely separate (MLN1783722).

CMS created four HCPCS modifiers that are more specific than 59 and asks you to use them first. CMS defines them as:

• XE: "Separate encounter, a service that is distinct because it occurred during a separate encounter."
• XP: "Separate practitioner, a service that is distinct because it was performed by a different practitioner."
• XS: "Separate structure, a service that is distinct because it was performed on a separate organ/structure."
• XU: "Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service."

Use 59 only when none of these, and no other modifier, describes the relationship. The appropriate situations, from CMS's MLN booklet:

1. Different anatomic sites at the same encounter (59 or XS): different organs, different anatomic regions, or in limited cases separate non-contiguous lesions. If an anatomic modifier fits (RT, LT, fingers, toes, eyelids, coronary arteries), use it instead.
2. Different encounters on the same day (59 or XE), when 24, 25, 27, 57, 58, 78, 79 or 91 doesn't describe it better.
3. Timed services in separate blocks (59 or XE): two timed codes performed one after the other, not mingled.
4. A diagnostic procedure that led to the therapeutic one (59 or XU), done first and clearly the basis for deciding to proceed.
5. A diagnostic procedure after a therapeutic one (59 or XU) that isn't a common, expected follow-up.

Which modifier fits?

Walk a line through the flow:

Can modifier 25 and 59 be billed together?

Yes, on different lines of the same claim. A visit with a separate problem gets 25 on the E/M; if two procedures that day form an NCCI pair but were done at different sites, the column 2 procedure gets XS or 59. What you can't do is put 59 on the E/M or 25 on the procedure.

Modifier 51 vs 59

They answer different questions:

• Modifier 51 says more than one procedure was done in the same session. It triggers the multiple procedure payment reduction: Medicare ranks the procedures and pays 100% of the highest-valued one and 50% of the second through fifth for codes with the standard indicator (ch. 12, §40.6). Medicare contractors also detect multiple surgeries without the modifier, so the reduction applies either way.
• Modifier 59 says a procedure was separate from another one in an NCCI edit pair. It doesn't reduce anything; without it, the bundled code isn't paid at all.

A claim can need both: two procedures in an NCCI pair at different sites carry 59 (or XS) to get paid at all, and the multiple-procedure reduction still applies to the lower-valued one.

Modifier 24 vs 25

Both go on E/M codes, and both relate to surgery. The difference is timing:

Routine postoperative follow-up is included in the global surgery payment and takes neither modifier. The global surgery period for each code is shown on its code page.

FAQ

When to use modifier 25 vs 59?

Use 25 on an E/M visit that was separately identifiable from a same-day procedure. Use 59 (or XE, XP, XS, XU) on a procedure, test or therapy service that an NCCI edit bundles with another procedure, when the two were truly separate. If you're modifying an E/M, it's never 59.

Can modifier 25 and 59 be billed together?

Yes, on different lines: 25 on the E/M and 59 or an X modifier on the procedure that needs to bypass an NCCI edit.

What are common modifier 25 mistakes?

Appending it to every visit with a procedure, using it when the visit was only the evaluation that led to a minor procedure, using it to bill two E/M visits on the same day, and appending it to a procedure code instead of the E/M.

Does modifier 25 require a different diagnosis?

No. Medicare states that different diagnoses aren't required for an E/M with modifier 25 on the same day as a procedure. The documentation has to show separate work.

Should I use XU or 59?

Use XU, XE, XS or XP whenever one accurately describes why the services were separate. CMS asks providers to use 59 only when no more specific modifier applies. Some commercial payers still prefer 59; check their policy.

Does modifier 59 reduce payment?

No. Modifier 59 has no payment effect of its own. It lets a code that would otherwise be denied under an NCCI edit be paid. Any reduction comes from other rules, such as the multiple procedure reduction.

Keep reading

• Modifier pages: 25, 59, 51, XU, XE, XS, XP, 24, 57.
• Physical therapy billing codes: when 59 or XE appears on timed therapy codes.
• Incident-to billing: who bills a visit performed by an NPP.
• What is an RVU?: the values behind the multiple procedure reduction.
• Codes in this guide: 99213 99214 11102 17000 20610

Sources: CMS MLN1783722, Proper Use of Modifiers 59, XE, XP, XS & XU (April 2026); Medicare Claims Processing Manual, Pub. 100-04, ch. 12, §§30.6.6, 40.1 and 40.6; Medicare NCCI Policy Manual, ch. 1. Verified October 6, 2026.