CPT Code 99310: Overview for healthcare billing

Key Takeaways

CPT Code 99310 reports subsequent nursing facility care, per day, for patients requiring high complexity medical decision making or 45-59 minutes of total time.

Code level is selected on medical decision making or total time only – the history and exam key components were eliminated for nursing facility visits effective January 1, 2023. 99310 is the highest-level code in the 99307-99310 family.

CPT 99318 (annual nursing facility assessment) was deleted effective January 1, 2023 – those visits are now reported using 99307-99310, including 99310 for the most complex cases.

Pabau’s claims management software helps nursing facility practices tighten documentation and submit cleaner claims, reducing the audit risk that CGS prepayment reviews have flagged for 99310.

CPT Code 99310 is a per-day billing code for subsequent nursing facility care involving high complexity medical decision making, or 45-59 minutes of total time on the date of the encounter. It is the highest-level code in the 99307-99310 subsequent nursing facility care series, used for the evaluation and management of patients in skilled nursing, intermediate care, and long-term care settings.

CPT Code 99310 is the highest-level code in the subsequent nursing facility care series (99307-99310), used for per-day evaluation and management visits involving high complexity. This guide covers the clinical description, key component requirements, time-based billing thresholds, the 2023 changes that deleted CPT 99318, Medicare reimbursement, and the audit patterns that CGS has flagged for this code.

CPT Code 99310: Clinical description and official definition

According to the American Medical Association’s CPT code set, CPT Code 99310 covers subsequent nursing facility care, per day, for the evaluation and management of a patient. It is the highest-complexity code within the 99307-99310 range, intended for visits where the patient’s condition demands either high complexity medical decision making or a substantial amount of provider time.

The code applies across skilled nursing facilities (SNFs), intermediate care facilities (ICFs), and long-term care settings. It is a per-day code, meaning only one unit may be billed per calendar day per provider. Both physicians and qualified non-physician practitioners (NPPs) may report it, subject to their applicable scope of practice and supervision requirements.

CPT 99318 (annual nursing facility assessment) was deleted effective January 1, 2023, as confirmed by AAFP Family Practice Management; those visits are now reported with the 99307-99310 codes based on the complexity of the encounter.

Practices that still reference 99318 in their documentation or charge capture workflows are coding from an obsolete framework. For a broader look at how these changes affect direct primary care software and workflow planning, the clinical context matters beyond just the code number.

The 99307-99310 code family: side-by-side comparison

CPT Code 99310 sits at the top of the subsequent nursing facility care series. Each code in the family corresponds to a progressively higher level of clinical complexity – from CPT 99308 for lower-complexity subsequent visits up to 99310, with CPT 99305 covering initial nursing facility care.

Selecting the wrong level – either upcoding 99310 when documentation supports only a lower-level visit, or undercoding – carries billing and compliance consequences.

Since January 1, 2023, code level across the family is selected on medical decision making or total time alone – the history and exam are documented as clinically appropriate but no longer determine the level.

For CPT Code 99310, the MDM must reflect high complexity under the AMA’s 2021 revised MDM guidelines, accounting for the number and complexity of problems addressed, the amount and complexity of data reviewed, and the risk of complications or morbidity associated with the treatment plan.

CPT Code 99310 documentation requirements

Documentation failures are the primary reason CPT Code 99310 claims are denied or downgraded on review. The CGS Medicare prepayment review of 99310 claims found that many notes lacked sufficient detail to support the level of service billed.

Because the level is now set by MDM or total time, the record must clearly support high complexity decision making – and, while no longer scored for code selection, a thorough history and exam still document the medical necessity behind that complexity.

Detailed interval history

The interval history must describe changes in the patient’s condition since the last visit, active problems, and relevant review of systems. “Patient doing well” or a single-line status update does not meet the threshold. The note needs to reflect the clinical complexity that warrants a high-level visit.

Detailed examination

A detailed examination involves an extended multi-system exam or a comprehensive single-organ system exam. The documentation must specify body areas or organ systems examined, with findings recorded – not templated filler. Generic phrases like “exam within normal limits” without specifics undermine the claim.

High complexity medical decision making

High complexity MDM under the AMA’s revised 2021 framework is built on three elements: the number and complexity of problems addressed, the amount and complexity of data reviewed, and the risk of complications or morbidity from the treatment plan.

To reach high complexity, at least two of these three elements must meet the high level – for example, a problem of high complexity (such as a life-threatening condition), extensive data review (external records, ordering and reviewing tests, independent interpretation), or high risk (drug therapy requiring intensive monitoring or a decision about hospitalization). All three elements should be individually addressed in the note.

Maintaining HIPAA-compliant documentation practices for primary care and similar settings reinforces the record integrity needed to support high-complexity E/M claims. Practices using structured patient records that prompt for each MDM element reduce the risk of incomplete documentation reaching the claim stage.

Medical decision making and time-based billing for 99310

CPT Code 99310 may be reported based on either medical decision making or total time. The time-based pathway became available for nursing facility E/M codes following the 2023 coding changes, aligning them with the office visit coding reforms introduced in 2021.

Time thresholds and prolonged services

When billing by time, CPT Code 99310 applies when the total time spent on the date of service is 45-59 minutes. Time includes face-to-face contact plus non-face-to-face work on that calendar day: reviewing records, ordering tests, documenting the note, and communicating with other providers. The total must be clearly documented in the medical record.

When time exceeds 60 minutes, prolonged service add-on codes apply. CPT 99418 is the standard add-on code for prolonged services beyond the 45-59 minute base of 99310. Each additional 15 minutes of time adds one unit of 99418.

For Medicare billing, CPT 99418 converts to HCPCS code G0317 – a distinction practices must handle correctly in their billing systems. Coding workflows similar to those used for other procedure codes (such as IVF CPT codes that involve add-on codes) require the same attention to code pairing rules.

Unlike the key component pathway, time-based documentation does not require meeting the high complexity MDM threshold. The note must instead clearly state the total time spent and describe the medical necessity for the time invested.

Practices should note that time thresholds for the 99307-99310 series were subject to proposed telehealth flexibility updates through 2024; verify current CMS policy for the applicable service date before billing telehealth visits under this code family.

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Medicare reimbursement rates and place of service rules

Medicare reimbursement for CPT Code 99310 is set annually through the Medicare Physician Fee Schedule (MPFS). Rates vary by geographic locality and are adjusted by conversion factors that CMS updates each year.

The CMS Physician Fee Schedule lookup tool provides the current year’s reimbursement amounts by locality for any given code, including 99310. Always verify against the current year’s schedule before relying on a published figure, as annual adjustments can shift the national average meaningfully.

For place of service, CPT Code 99310 requires a nursing facility setting. The appropriate Place of Service (POS) codes are:

• POS 31 – Skilled Nursing Facility (SNF), for patients requiring skilled nursing or rehabilitation
• POS 32 – Nursing Facility (NF), for intermediate care and long-term care facilities
• POS 54 – Intermediate Care Facility/Individuals with Intellectual Disabilities (ICF/IID)

Billing CPT 99310 with an incorrect POS code is a frequent audit trigger. The POS determines the facility vs. non-facility payment rate – an error here changes the reimbursement calculation and can flag a claim for review. Sound medical practice business planning includes verifying POS accuracy as a standard pre-submission step, particularly for practices billing across multiple facility types.

Federally mandated visit requirements

CMS regulations require physicians to visit nursing facility patients within specified timeframes. CPT codes 99307-99310 are used to report these federally mandated visits, as well as any additional medically necessary visits. When the stay ends, discharge day management is reported separately with CPT 99316.

The code selected must match the complexity of care delivered on that specific visit date – a routine mandated visit where the patient is stable is unlikely to support 99310 without exceptional clinical circumstances.

Audit risk and common billing errors for 99310

CGS Administrators, a Medicare Administrative Contractor (MAC), conducted a prepayment medical review of CPT Code 99310 claims and published its findings. The review identified several recurring patterns that practices should address systematically.

Patterns CGS identified in 99310 claim reviews

• Missing interval history: Notes lacked documentation of the patient’s condition changes since the previous visit, reducing them to insufficient for 99310.
• Templated exam documentation: Pre-populated exam fields that weren’t customized to the patient’s actual presentation were flagged as not supporting the level billed.
• MDM not addressed: Providers documented clinical actions without explicitly connecting them to the MDM elements – particularly the data reviewed and the risk of treatment decisions.
• Incorrect code for annual assessments: After CPT 99318 was deleted in 2023, some practices continued using it or misapplied the replacement logic. Annual assessments must now be reported using whichever 99307-99310 code matches the complexity of that visit.
• Place of service mismatches: Claims billed with POS codes inconsistent with the facility type where care was delivered.

Practices using claims management software that flags incomplete documentation fields before submission can catch many of these issues at the point of care. Standard billing workflows for high-complexity codes should include a pre-submission checklist aligned to the CGS documentation requirements. The same structured approach that reduces errors for other E/M code families (such as coaching CPT codes used in behavioral health) applies to nursing facility billing as well.

Practices handling documentation for cognitive assessments (such as ADHD screening CPT code workflows) often face similar documentation completeness challenges as 99310 – both require structured record-keeping to survive payer review. Combining digital intake forms with automated workflow prompts reduces the manual burden of capturing all required elements consistently across visits.

Conclusion

CPT Code 99310 is the highest-complexity tool available for subsequent nursing facility care, but it is also one of the most audit-scrutinized codes in the E/M series. Billing it successfully comes down to documentation discipline – capturing all three MDM elements, and the total time when relevant, with enough specificity to withstand a payer review.

Pabau’s claims management software gives nursing facility and long-term care practices the workflow structure to build compliant 99310 documentation into every visit, not just the ones flagged for audit. To see how it fits your billing process, book a demo.

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