Acute Hospital Case Mix Data Submissions

Overview

CHIA collects quarterly hospital case mix data on patient demographics, diagnoses and procedures, physicians, and charges for inpatient discharges, outpatient observation stays, and emergency department visits in Massachusetts. Hospitals must follow the Case Mix Data Specification Manuals for instructions on data file formats, data element definitions, code tables, and data quality standards. Hospitals are required to submit inpatient discharge data, emergency department data, and outpatient observation data.

Submission Deadlines

Case Mix data files must be submitted quarterly according to the following schedule:

Q1 (10/1-12/31) by 3/16
Q2 (1/1-3/31) by 6/14
Q3 (4/1-6/30) by 9/13
Q4 (7/1-9/30) by 12/14

Preliminary inpatient discharge, emergency department, and outpatient observation files are due by the last day of the month following the close of the quarter.

FY 2026 Submission Resources

FY25 HIDD Submission Guide (PDF) FY25 EDD Submission Guide (PDF) FY26 OOD Submission Guide (PDF) File Encryption/Submission Instructions (PDF) Transfer Org ID List (Excel) CDC Ethnicity Codes (PDF) Payer Type/Source Codes (Excel)

Registration Instructions

New users must register to submit data via CHIA Submissions.

Complete User Agreement

Complete and sign the CHIA Data Reporter User Agreement (DRUA) after reviewing the DRUA instructions. Note that each individual user for an organization must complete the form.

Submit User Agreement

Submit the completed Data Reporter User Agreement to DL-Data-Submitter-HelpDesk@chiamass.gov. You will be notified when your account is ready to use.

For help with registration, email DL-Data-Submitter-HelpDesk@chiamass.gov or call 617-701-8100 (9am-5pm Monday through Friday).

Technical Assistance

CHIA occasionally hosts Case Mix Technical Assistance Group (TAG) webinar meetings at which hospitals or facilities can ask questions about provider data submissions. Look for upcoming meetings below or review presentation materials from previous TAG webinars.

There are currently no upcoming meetings. Check back soon.

Archived Documentation

FY 2026

FY 2025

Case Mix

Access Massachusetts hospital case mix data, including inpatient discharge, emergency department, and outpatient observation datasets, documentation, and data specification manuals.

CHIA Regulations (CMR)

Access CHIA's regulations governing health care data collection and reporting in Massachusetts, including current rules, administrative bulletins, and hearings.