0421U
What 0421U is
This code appears in the Medicare NCCI edit tables. It has no RVUs in the CY2026 Physician Fee Schedule file.
Medically Unlikely Edit (MUE)
Medicare caps 0421U at 1 unit per date of service for practitioner claims (MAI 2 - date of service edit (absolute): units above the MUE never pay), rationale: Code Descriptor / CPT Instruction. Units above the cap are denied unless the edit's adjudication rules allow an appeal with documentation.
Billed with 0421U? These codes are bundled into it
0421U is a Column 1 code in 69 active NCCI PTP edits. When one of these Column 2 codes is reported on the same date of service, it is denied as bundled - unless the edit's modifier indicator is 1 and documentation supports a distinct service with an NCCI-associated modifier.
| Column 2 code | Short description | Modifier indicator | |
|---|---|---|---|
0091U | 0 - no modifier bypass | Check pair | |
0111U | 1 - modifier may bypass | Check pair | |
0212U | 1 - modifier may bypass | Check pair | |
0213U | 1 - modifier may bypass | Check pair | |
0229U | 1 - modifier may bypass | Check pair | |
0453U | 0 - no modifier bypass | Check pair | |
0496U | 1 - modifier may bypass | Check pair | |
0501U | 0 - no modifier bypass | Check pair | |
80503 | Path clin consltj sf 5-20 | 1 - modifier may bypass | Check pair |
80504 | Path clin consltj mod 21-40 | 1 - modifier may bypass | Check pair |
80505 | Path clin consltj high 41-60 | 1 - modifier may bypass | Check pair |
81201 | Apc gene full sequence | 1 - modifier may bypass | Check pair |
81202 | Apc gene known fam variants | 1 - modifier may bypass | Check pair |
81203 | Apc gene dup/delet variants | 1 - modifier may bypass | Check pair |
81210 | Braf gene | 1 - modifier may bypass | Check pair |
81228 | Cytog alys chrml abnr cgh | 1 - modifier may bypass | Check pair |
81229 | Cytog alys chrml abnr snpcgh | 1 - modifier may bypass | Check pair |
81275 | Kras gene variants exon 2 | 1 - modifier may bypass | Check pair |
81276 | Kras gene addl variants | 1 - modifier may bypass | Check pair |
81288 | Mlh1 gene | 1 - modifier may bypass | Check pair |
81292 | Mlh1 gene full seq | 1 - modifier may bypass | Check pair |
81293 | Mlh1 gene known variants | 1 - modifier may bypass | Check pair |
81294 | Mlh1 gene dup/delete variant | 1 - modifier may bypass | Check pair |
81295 | Msh2 gene full seq | 1 - modifier may bypass | Check pair |
81296 | Msh2 gene known variants | 1 - modifier may bypass | Check pair |
81297 | Msh2 gene dup/delete variant | 1 - modifier may bypass | Check pair |
81298 | Msh6 gene full seq | 1 - modifier may bypass | Check pair |
81299 | Msh6 gene known variants | 1 - modifier may bypass | Check pair |
81300 | Msh6 gene dup/delete variant | 1 - modifier may bypass | Check pair |
81301 | Microsatellite instability | 1 - modifier may bypass | Check pair |
Showing 30 of 69 column 2 codes. Use the pair checker for any specific combination.
0421U is bundled into these codes
0421U appears as a Column 2 code in 61 active edits. Reported with one of these Column 1 codes on the same date of service, 0421U is the code that denies.
| Column 1 code | Short description | Modifier indicator | |
|---|---|---|---|
0101U | 1 | Check pair | |
0102U | 1 | Check pair | |
0103U | 1 | Check pair | |
0129U | 1 | Check pair | |
0163U | 0 | Check pair | |
0238U | 1 | Check pair | |
0239U | 1 | Check pair | |
0242U | 1 | Check pair | |
0244U | 1 | Check pair | |
0306U | 1 | Check pair | |
0307U | 1 | Check pair | |
0326U | 1 | Check pair | |
0331U | 1 | Check pair | |
0340U | 1 | Check pair | |
0460U | 1 | Check pair |
Data: CMS CY2026 Physician Fee Schedule RVU file (October release, RVU26D) and Medicare NCCI PTP practitioner edits v32.3 (2026 Q4). Verify against the official files before billing or contracting decisions.