UB04 Field 3a: Patient Control Number

Introduction

UB-04 Field 3a, also known as Box 3a, is used to record the Patient Control Number. This unique alphanumeric identifier is assigned by the provider to facilitate the tracking and reconciliation of individual patient accounts within their internal billing system.

Requirements

Requirement Type	Status
Inpatient Requirement	Optional
Outpatient Requirement	Optional

Billing Tips

While Field 3a is designated as optional, it is highly recommended for efficient revenue cycle management. The value entered in Box 3a is typically reflected on the Explanation of Benefits (EOB) or Electronic Remittance Advice (ERA), allowing billing staff to quickly reconcile payments and identify specific patient accounts without relying solely on the Medical Record Number.