DEX Test Registration and Claims Submission (M00148, V14)

To access and obtain a DEX Z-CodeTM identifier, follow these steps.

  • Go to the DEXTM Diagnostics Exchange:
  • Select "Register My Organization" and follow the prompts, including participation in the MolDX program
  • Within 10 business days of registering with DEX, you will receive a welcome email with a link to set your password and a "getting started" guide
  • Once you have received the email and activated your login, you will have access to add test information
  • Within 45 business days of entering specific test information, the DEX Z-CodeTM identifier will be assigned to tests. DEX will send an email to you when the DEX Z-Code has been assigned.
  • Please note: we recommend waiting 2–3 weeks before adding this Z-Code to your claim
  • Once DEX assigns a Z-Code, it is not effective until the MolDX team has reviewed your test application to determine coverage and assigned a CPT® code. The CPT code you submit with your application is not necessarily the CPT code that MolDX will assign to your test. You must submit the correct combination of Z-Code, CPT code and NPI in order for claims to be paid.

DEX access enables the following functions:

  • Review specific test information
  • Review each DEX Z-CodeTM identifier
  • Request edits for tests
  • Register new tests

For questions, email

As the individual listed in the DEX Z-CodeTM identifier application, the username is specific to the contact person designated by each laboratory. Please do not forward or share this information. Colleagues within your organization who want to register may apply for a public user account at A public user account requires a valid email address and allows a view of public information.

Within 45 business days of a complete and valid registration, the DEX Z-CodeTM identifier will be assigned for tests.

The MolDX team will review the registry information to determine if a test meets the Medicare criteria for coverage. For more information, please refer to MolDX Frequently Asked Questions.

MolDX Claim Submission
The claim line for molecular diagnostic tests must contain the appropriate CPT code and test identifier (DEX Z-CodeTM) associated with the test.   

For CPT NOC codes (81479, 81599, 84999, 85999, 86849, 87999), the test specific DEX Z-Code™ is submitted in the SV101-7 (5010A1-837P) or SV202-7 (5010A1-837I) claim line detail field. For CPT non-NOC codes, providers may either use the SV101-7 or SV202-7 (preferred) or the NTE field to submit this required information.

Providers billing Part A for molecular tests performed by a proprietary or reference laboratory must obtain the DEX Z-Code™ for the molecular test(s) from the performing laboratory. Part A providers billing for molecular services performed by a hospital-based laboratory must register and obtain a unique DEX Z-Code™ for each molecular test in the MolDX code ranges designated above. Part A providers will need to specify which lines are billed for MolDX and the appropriate DEX Z-CodeTM per line within the remarks section of the claim.

For correct claims adjudication for the applicable services, enter the following information for each test submitted on the claim:

  • Enter claim line number of the performed test
  • Enter registered test DEX Z-CodeTM

Correct FISS Remarks Sample

Sample 1: ID for a test on line one

Line 1 (HCPCS) – ZB123

Sample 2: IDs for two molecular tests on line one and line two

Line 1 (HCPCS) – ZB123
Line 2 (HCPCS) – ZD456

Last Updated: 03/01/2021