S5100 HCPCS Code: Day care services (Units, EVV, Rates, Denials)
S5100: Day care services, adult, per 15 minutes. Billing unit, which services it covers, modifiers, whether EVV applies, typical rate notes by state and the common denial reasons.
S5100 is “Day care services, adult; per 15 minutes.” It is billed per 15 min and covers time a participant spends at an adult day center. Medicare does not pay it. EVV does not apply, because the service is delivered at the center, not in the home.
Units and rounding
One unit is 15 minutes of attendance, so 1 hour is 4 units. Your state sets the rule for partial units and may cap the units per day. Some programs bill adult day by the half day or day instead; see S5101 and S5102. Convert minutes in the units calculator.
Modifiers you will see
- U1–U9: State-defined; often distinguish programs (waiver vs state plan), service levels or provider types
- TF / TG: Intermediate or complex level of care, where the state uses levels
Modifier meanings are set by each state and payer, so check your provider manual. See home care billing modifiers.
Typical rates
Adult day rates are set per state program and managed-care plan, and some states pay a higher rate for health-model (medical) adult day. Each state program and managed-care plan sets its own rate, so use your state’s current fee schedule.
Common denial reasons
- Units exceed the authorization
- Attendance records missing arrival and departure times
- Billing 15-minute units on a day already billed as a half day or full day
- Service date outside the authorization period
Related codes
Source
CMS HCPCS Level II code set (quarterly update). Confirm the exact descriptor and any state-specific unit definition in your payer’s billing manual. Last reviewed November 6, 2026.
General information, not billing or legal advice. Check your state Medicaid agency’s current fee schedule and provider manual.