Double-Charge Detector 0420U

Onc urthl mrna xprsn 6 snp — 247 bundling rules

If your bill lists 0420U alongside any of these codes as separate charges, it may be an unbundling error.

By Elena Vasquez , Medical Billing Research Lead · Published March 15, 2026 · Updated April 3, 2026

About the analyst

Elena Vasquez leads hospital billing pattern analysis at BillRazor Research. She focuses on identifying overcharges, markup outliers, and patient advocacy strategies. Expertise: hospital billing patterns, overcharge analysis, patient advocacy.

NCCI edit data

247 code pairs

Updated 2026-04-03

Bundling rules — 0420U

NCCI edits: these codes have billing restrictions when billed with 0420U

Research suggests 49–80% of hospital bills contain errors. Our system checks every line item against Medicare benchmarks.

Common unbundling errors — medical procedures

Unbundling occurs when medical providers bill two separate codes for services that should be combined into a single charge according to National Correct Coding Initiative (NCCI) rules. In other procedures including anesthesia, radiology, pathology, and miscellaneous support services, common unbundling patterns include separately billing diagnostic imaging with its professional interpretation when both should be included in one comprehensive code, and charging for basic monitoring or preparation services alongside the primary procedure when these components are considered integral parts of the main service. Another frequent error involves billing multiple pathology examination codes for what constitutes a single comprehensive analysis. With 809 other codes subject to bundling restrictions in the NCCI database, these errors create charges above the benchmark for patients who receive multiple bills for what should constitute one complete service. The potential difference between unbundled billing and correct coding practices can significantly impact patient financial responsibility, as they may face duplicate charges for components of care that medical coding standards define as a single billable service.

What to check on your bill

When reviewing itemized bills for procedure bundling issues, patients should examine several key areas to identify potential billing irregularities. Look for multiple procedure codes billed on the same date that represent components of a comprehensive service, such as separate charges for incision, repair, and closure when these steps are typically included in one primary procedure code. Watch for code patterns where related procedures share the same first three digits, as these often indicate services that should be bundled together under Medicare's Correct Coding Initiative. Check for appropriate modifier usage, particularly modifier 59 or XS, which legitimately allow separate billing when procedures are performed on different anatomical sites or during distinct sessions. Without proper modifiers, separately billed related procedures may represent charges above the benchmark. Compare your itemized statement against standard bundling practices for your specific procedure type to identify potential differences in billing patterns.

All bundling rules for 0420U

247 code pairs that have billing restrictions with this procedure.

Never bill together

243

May bill with modifier

Code	Description	Rule
0011M	Onc prst8 ca mrna 12 gen alg	Never bill together
0013M	Onc mrna 5 gen recr urthl ca	Never bill together
0021U	Onc prst8 detcj 8 autoantb	Never bill together
0029U	Rx metab advrs trgt seq alys	May bill with modifier
0030U	Rx metab warf trgt seq alys	May bill with modifier
0034U	Tpmt nudt15 genes	May bill with modifier
0070U	Cyp2d6 gen com&slct rar vrnt	May bill with modifier
0086U	Nfct ds bact&fng org id 6+	May bill with modifier
0111U	Onc colon ca kras&nras alys	May bill with modifier
0140U	Nfct ds fungi dna 15 trgt	May bill with modifier
0141U	Nfct ds bact&fng gram pos	May bill with modifier
0142U	Nfct ds bact&fng gram neg	May bill with modifier
0156U	Copy number sequence alys	May bill with modifier
0169U	Nudt15&tpmt gene com vrnt	May bill with modifier
0177U	Onc brst ca dna pik3ca 11	May bill with modifier
0212U	Rare ds gen dna alys proband	May bill with modifier
0213U	Rare ds gen dna alys ea comp	May bill with modifier
0229U	Bcat1&ikzf1 prmtr mthyln aly	May bill with modifier
0232U	Cstb full gene analysis	May bill with modifier
0234U	Mecp2 full gene analysis	May bill with modifier
0235U	Pten full gene analysis	May bill with modifier
0239U	Trgt gen seq alys pnl 311+	May bill with modifier
0242U	Trgt gen seq alys pnl 55-74	May bill with modifier
0244U	Onc solid orgn dna 257 genes	May bill with modifier
0252U	Ftl aneuploidy str alys dna	May bill with modifier
0253U	Rprdtve med rna gen prfl 238	May bill with modifier
0286U	Cep72 nudt15&tpmt gene alys	May bill with modifier
0318U	Ped whl gen mthyltn alys 50+	May bill with modifier
0321U	Iadna gu pthgn 20bct&fng org	May bill with modifier
0326U	Trgt gen seq alys pnl 83+	May bill with modifier
0331U	Onc hl neo opt gen mapping	May bill with modifier
0336U	Rare ds whl gen seq bld/slv	May bill with modifier
0341U	Ftl aneup dna seq cmpr alys	May bill with modifier
0347U	Rx metab/pcx dna 16 gen alys	May bill with modifier
0348U	Rx metab/pcx dna 25 gen alys	May bill with modifier
0349U	Rx metab/pcx dna 27gen rx ia	May bill with modifier
0350U	Rx metab/pcx dna 27 gen alys	May bill with modifier
0363U	Onc urthl mrna 5 gen alg	May bill with modifier
0365U	Onc bldr 10 ur hrbr urthl ca	May bill with modifier
0366U	Onc bldr 10 prb recr bldr ca	May bill with modifier
0367U	Onc bldr 10 flwg trurl rescj	May bill with modifier
0452U	Onc bldr mthyl penk lte-qmsp	May bill with modifier
80503	Path clin consltj sf 5-20	May bill with modifier
80504	Path clin consltj mod 21-40	May bill with modifier
80505	Path clin consltj high 41-60	May bill with modifier
81105	Hpa-1 genotyping	May bill with modifier
81106	Hpa-2 genotyping	May bill with modifier
81107	Hpa-3 genotyping	May bill with modifier
81108	Hpa-4 genotyping	May bill with modifier
81109	Hpa-5 genotyping	May bill with modifier

Showing 50 of 247 rules. Show all

FAQ — medical procedure bundling

What is NCCI bundling and what does 'bundled' mean on a medical bill?

NCCI bundling refers to the National Correct Coding Initiative rules that prevent certain procedure codes from being billed separately when performed together. When codes are bundled, one procedure is considered inclusive of another, meaning only the primary procedure should be billed rather than charging for each component separately.

How can I identify if codes were incorrectly unbundled on my bill?

Incorrectly unbundled codes appear as separate line items on your bill when NCCI rules indicate they should be grouped together under one primary procedure code. This typically occurs with anesthesia, radiology, pathology, and miscellaneous support services that are considered integral to the main procedure being performed.

What should I do if I find unbundled charges on my medical bill?

Contact your healthcare provider's billing department to request a review of the charges and provide documentation showing the NCCI bundling rules that apply. Request an itemized explanation of why the codes were billed separately and ask for a corrected bill that reflects proper bundling if no valid modifier justification exists.

When is it legitimate to use modifiers to override NCCI bundling rules?

Modifiers are appropriately used when procedures are performed on different anatomical sites, during separate patient encounters, or when distinct procedural services are provided that don't fall under the bundling restrictions. The modifier usage must be supported by clear documentation in the medical record that demonstrates the services were truly separate and distinct from the bundled procedure.

Rates shown are from the 2026 Medicare Physician Fee Schedule and CMS IPPS. BillRazor compares your bill against these data sources. See how it works →

Data source: CMS National Correct Coding Initiative (NCCI) Procedure-to-Procedure (PTP) edits, updated quarterly. These code pairs are maintained by CMS to prevent improper billing of services that should be billed as a single procedure.

What this means: When two codes are listed as an NCCI edit pair, billing them separately on the same date of service is typically incorrect. "Never bill together" means no modifier can override the rule. "May bill with modifier" means the codes can be billed separately with appropriate documentation.