HCPCS code S0320 – Tamoxifen chemoprevention billing guide

Key takeaways

HCPCS Code S0320 reports telephone calls by a registered nurse to a disease management program member for monitoring, billed as one unit per month.

S0320 is a temporary national S-code, added to the HCPCS file on October 1, 2002, and CMS lists it as not payable by Medicare.

Commercial insurers and some Medicaid plans that contract for disease management decide whether S0320 pays, at what rate, and with what proof.

A clean S0320 claim rests on proof of program enrollment, an RN call log for the month, and a diagnosis for the condition being managed.

S0320 is not a drug code, since oral tamoxifen 10 mg is S0187 and no code S0321 exists in the HCPCS file.

What is HCPCS Code S0320?

HCPCS Code S0320 is the Level II code for telephone calls by a registered nurse to a disease management program member for monitoring. Its unit is one month. It belongs to the S-series, the temporary national codes that private insurers and Medicaid agencies use where no permanent code fits.

S0320 describes a nursing service. A registered nurse calls an enrolled program member to check on a chronic condition, and the practice reports one unit for that month of calls.

S0320 is sometimes confused with the drug S-codes around it. Oral tamoxifen citrate, 10 mg, is S0187, and there is no code S0321. The next code after S0320 in the HCPCS file is S0340.

S0320 official descriptor and HCPCS record

The table below is read from the CMS alpha-numeric HCPCS file, October 2026 release. Check the current HCPCS quarterly update before you rely on any field, because CMS can revise S-codes each quarter.

What S0320 covers and what it does not

S0320 captures nurse-led telephone monitoring inside a structured disease management program. Four parts of the descriptor decide whether a month of calls fits.

• Enrolled member: the patient is enrolled in a disease management program, usually one the payer runs or contracts for. A routine patient call outside a program does not fit.
• Registered nurse: an RN makes the calls. Calls by a medical assistant, a pharmacist or the physician fall outside the descriptor as written.
• Monitoring purpose: the call checks symptoms, readings, medicines and adherence against the care plan. Scheduling, billing and reminder calls are not monitoring.
• Per month: one unit covers the month of calls. The descriptor sets no minimum call count, so the payer contract decides how many calls a month needs.

Other program services have codes of their own. The initial program assessment is S0315, a reassessment is S0316, and a per diem program charge is S0317. Physician telephone and care management services are reported with CPT codes, not S0320.

Why Medicare does not pay for S0320

CMS assigns S0320 coverage code I, which the HCPCS record layout defines as not payable by Medicare. S-codes exist for private payers and Medicaid agencies, and Medicare contractors do not price them.

The pricing indicator 00 says the same thing from the payment side. Part B holds no fee schedule amount for S0320, so there is no Medicare allowed amount and no 80/20 split.

For an Original Medicare patient, comparable work is reported through Medicare care management codes. Chronic care management code 99490, for example, covers clinical staff time for a patient with two or more chronic conditions in a calendar month. It has its own consent, care plan and time rules, so read them before you switch codes.

Payer coverage for S0320

Payers that accept S0320 write their own policy. Coverage, rate and documentation rules come from the contract, not from a national fee schedule.

• Commercial insurers: some pay S0320 under a disease management contract. Many pay only contracted program vendors, so confirm your network status before the first call.
• Medicaid: state programs and Medicaid managed care plans decide whether to use S-codes at all. Check the state fee schedule and the plan billing manual.
• Medicare Advantage: these private plans can set their own coding rules. Confirm the plan contract covers S0320 before you bill it.

Ask four questions at verification. Does the plan accept S0320, which providers does it pay, what is the monthly rate, and does prior authorization apply? Record the answers and the call reference number on the patient account.

Documentation requirements for S0320

Payers that pay S0320 usually audit two facts. The member was enrolled in the program, and a registered nurse made monitoring calls that month. Keep proof of both in the record.

• Program enrollment: the enrollment date, the program and the condition it manages, plus the member’s agreement where the payer requires it.
• Care plan: the goals, the readings or symptoms the nurse monitors, and the rules for escalating a problem.
• Call log: for each call, the date, start time and duration, the nurse’s name and RN credential, and whether the member was reached.
• Call content: readings and symptoms reported, medication and adherence questions, education given, and any change to the plan.
• Escalations: any call that led to a provider review, a visit or an urgent referral, with the outcome.
• Monthly summary: the number of completed monitoring calls and the dates the billed unit covers.

An attempted call that never reaches the member is not monitoring. Log it anyway, but check the contract before you count it toward the month.

ICD-10-CM codes commonly paired with S0320

The diagnosis on an S0320 claim is the chronic condition the program manages. Code it to the highest specificity the record supports. The unspecified codes below illustrate common programs and are not a payer coverage list.

Confirm current code status in the CDC/NCHS ICD-10-CM browser tool. Replace an unspecified code whenever the record names the type.

How to bill S0320 step by step

Sort each month by payer before anyone builds a claim. The diagram shows where Original Medicare drops out and which four tests the remaining payers check.

1. Confirm enrollment. Check that the member is enrolled in a covered disease management program, and record the start date.
2. Verify the payer. Confirm the plan accepts S0320, pays your practice for it, and whether it requires prior authorization.
3. Make and log the calls. The registered nurse documents each call against the care plan on the day it happens.
4. Close the month. Count the completed monitoring calls and check them against any minimum in the contract.
5. Bill one unit. Report S0320 with one unit for the month, the diagnosis for the managed condition, and the dates the payer asks for.
6. Keep it off Medicare claims. Original Medicare does not pay S-codes, so use Medicare care management codes where the patient qualifies.
7. Post and reconcile. Post the remittance, and work any denial from its reason code before the filing limit runs out.

Related HCPCS codes near S0320

S0320 sits among the S-codes for disease management and care coordination. Each code below is active in the October 2026 HCPCS file. For codes outside this range, search the HCPCS code library.

Common S0320 denials and how to fix them

Most S0320 denials trace back to the payer, the contract or the unit count. The table maps each signal to its cause and fix.

How Pabau keeps S0320 call logs and claims on one record

Disease management billing breaks down when the call log, the enrollment record and the claim live in different places. A nurse logs calls in a spreadsheet, and the biller rebuilds the month from memory.

Pabau, the practice management platform we build, keeps all three on one patient record. Enrollment forms and the care plan sit in Pabau’s digital forms on the patient record. The nurse logs each call as a treatment note on the same record. Vitals and weight trends sit there too, so the nurse sees the last reading before the next call.

For US practices, Pabau’s claims management software submits CMS-1500 claims through Claim.MD and posts ERA remittances. Prior authorization codes, dates and sessions are tracked on the case, with a warning when one is missing.

Keep RN call logs and S0320 claims together

Pabau holds the enrollment forms, care plan and call notes on one patient record. Your team can track prior authorizations and submit the monthly claim from the same system.

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Conclusion

S0320 pays only where a contract says it does. The descriptor is narrow, covering an enrolled member, a registered nurse, monitoring calls and one unit a month. The payer decides the rest.

So the work comes before the first call. Confirm the plan accepts S0320 and pays your practice, then build the call log the payer will audit. Keep Original Medicare patients on Medicare care management codes instead.

Book a demo to see how Pabau keeps disease management call notes and monthly claims on one patient record.

Continue your research

Billing the daily program rate instead? HCPCS Code S0317 covers the disease management per diem and how it pairs with S0315 and S0316.

Reassessing a member mid-program? HCPCS Code S0316 covers the disease management follow-up and reassessment.

Need a framework for reducing claim rejections across your practice? Denial management in healthcare covers the workflow from root-cause analysis to appeal timelines.

Looking for documentation controls your team can follow consistently? Medical billing compliance outlines the controls that keep S-code and CPT claims clean across payer types.

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