Top ICD-10 Coding Mistakes That Trigger Denials

A practical guide for skilled nursing facility teams

By Chasity Henry, RN, RAC-CT, Clinical Reimbursement Consultant

Accurate ICD-10 coding depends on complete documentation, correct code selection, and consistent application of official guidance. Use this resource to identify common breakdowns before they affect claim submission or audit support.

1. The diagnosis is not supported by an authorized provider

Where claims become vulnerable: A diagnosis appears on the claim or assessment, but the record does not contain documentation from a practitioner legally accountable for establishing it. This can occur when teams rely on a problem list, medication, therapy observation, or documentation from another discipline.

Better practice: Confirm the diagnosis in current provider documentation. When the record is unclear or incomplete, follow the organization’s compliant query process before assigning the code.

2. The code is not specific enough

Where claims become vulnerable: An unspecified code is selected even though the record supports details such as site, laterality, condition type, or encounter information.

Better practice: Review the Alphabetic Index, Tabular List, instructional notes, and available clinical documentation. Assign the most specific code supported by the record rather than assuming missing details.

3. An inactive or historical condition is treated as current

Where claims become vulnerable: A diagnosis remains on the active list even though it has resolved or is not affecting the resident’s care, treatment, or assessment during the relevant period.

Better practice: Validate that each reported condition is current and meets applicable reporting requirements. Remove or appropriately distinguish resolved and historical conditions.

4. The diagnosis does not align with the services billed

Where claims become vulnerable: The selected diagnosis does not adequately support the medical necessity of the treatment or service reflected on the claim.

Better practice: Confirm that the diagnosis-to-service relationship is supported in the evaluation, plan of care, progress documentation, and claim. Resolve discrepancies before billing.

5. Required sequencing or combination-code guidance is missed

Where claims become vulnerable: Codes are reported in the wrong order, an underlying condition is omitted, or tabular instructions such as “code first,” “use additional code,” or Excludes notes are overlooked.

Better practice: Review al applicable tabular instructions and sequencing rules. Do not rely on habit, a facility cheat sheet, or code descriptions alone.

6. Documentation conflicts across the record

Where claims become vulnerable: Provider notes, nursing documentation, therapy records, the MDS, and billing information describe the condition differently.

Better practice: Create a review process that brings inconsistencies to the appropriate team member before the claim is submitted. Coding should reflect one clinically supported story.

7. Outdated codes or guidance are used

Where claims become vulnerable: The team carries forward an invalid code or relies on an older code set after annual or midyear updates take effect.

Better practice: Use the code set and official guidance that apply to the date of service. Update software, reference materials, education, and internal tools on a defined schedule.

Pre-Submission Review

☐ Provider documentation supports every reported diagnosis.

☐ The code reflects the highest specificity available in the record.

☐ The condition is current and relevant to the reporting period.

☐ Alphabetical Index and Tabular instructions, sequencing rules, and Excludes notes were reviewed.

☐ The diagnosis supports the services biled and the documented plan of care.

☐ The record presents a consistent clinical picture across disciplines.

☐ The current code set and official guidelines were used.

A stronger process starts before billing. Routine validation, current references, and clear communication can help teams identify unsupported or inconsistent coding before it becomes a denial issue.

This guide is intended for general education and does not replace official ICD-10-CM guidance, payer requirements, or review by a qualified coding professional. Always apply the rules and documentation requirements relevant to the resident, setting, payer, and date of service.