Medicaid member ID formats: what a valid ID looks like in each state, and how a biller catches a bad one
Overview
There is no national Medicaid ID format, so each state sets its own. Illinois and Texas use 9 digits, Michigan and Utah 10, Indiana and Ohio 12, Arizona a letter plus 8 digits, New York 8 characters like LL#####L, and Washington 9 digits followed by WA. Count the characters and match the name, birth date and sex to the payer's eligibility record before billing.
On this page
A Medicaid member ID is the number a state assigns to one rider, and a claim needs it exactly as the payer holds it. Each state uses its own length and mix of letters and digits, so a biller who works with several payers cannot rely on one rule. How to confirm a rider is covered is a separate step, covered in verifying eligibility. The ID that identifies your own company is the Medicaid provider number.
What each state’s ID looks like
These ten states describe their format in a companion guide, manual or form. The shortest is 8 characters and the longest is 12.
| State | Format | Name the state uses |
|---|---|---|
| Arizona | 9 characters, a letter then 8 digits, as in A12345678 | AHCCCS Member ID |
| Illinois | 9 digits | Recipient Identification Number |
| Indiana | 12 digits | IHCP Member ID |
| Michigan | 10 digits | Beneficiary ID |
| New York | 8 characters, as in LL#####L | Medicaid Identification Number |
| Ohio | 12 digits | Ohio Medicaid Billing Number |
| South Dakota | 9 digits | Recipient ID |
| Texas | 9 digits, first digit 1 through 7 | Medicaid number |
| Utah | 10 digits | Beneficiary ID |
| Washington | 9 digits followed by WA | ProviderOne client ID |
The documents behind the grid range from Ohio’s 2015 form to Michigan’s October 2026 manual, so a state that has since changed its format will show a different pattern on a current card. Texas also reserves numbers that begin with 9 for the Children with Special Health Care Needs Services Program.
Why the card, the state ID and the plan ID can differ
The claim form asks for the number assigned by the payer you are billing. NUCC’s instruction for item 1a says to enter the ID as it appears on the insured’s card for that payer, and to use the unique member number the payer assigned if there is one. Four things can change the number you find:
- A suffix on the card. South Dakota’s card carries a three-digit generation number beside the nine-digit ID. It is not part of the ID, and it stays off the claim.
- A second number in the system. Michigan’s card shows a beneficiary ID, but the manual tells billers to use the 10-digit number returned by its CHAMPS eligibility inquiry.
- More than one document. California’s temporary paper ID cards carry a 14-character BIC ID, and its Eligibility Confirmation Letter shows the Client Identification/Index Number.
- A different payer. A health plan may issue its own member number, and that is the one to use on a claim billed to that plan.
Catching a bad ID before the claim goes out
- Count. Compare the length with the state’s format. A 9-digit number where Indiana expects 12 will not match.
- Check the pattern. New York’s example is two letters, five digits and a letter, Arizona’s starts with a letter, Washington’s ends in WA, and a Texas Medicaid number begins with 1 through 7.
- Drop what is not part of the ID. Leave off the South Dakota generation number.
- Match the rider’s details. In Texas the claim has to carry the same name, birth date, sex and nine-digit number that TMHP holds on file, and Illinois asks for names as they appear on the card.
- Look the rider up. Texas providers can send an interactive request through TexMedConnect or call the Automated Inquiry System at 800-925-9126.
A bad ID comes back as CARC 31 or CARC 140, or as remark code N382. The CARC entry lists the rest, and a claim rejection explains why a claim stopped at the front end can be fixed and sent again.
Frequently asked questions
- Is the number on the Medicaid card the number I bill?
- Often, but not always. South Dakota's card shows a three-digit generation number that is not part of the ID and must stay off the claim. Michigan says to bill the 10-digit beneficiary ID from its eligibility inquiry. California's temporary paper cards show a 14-character BIC ID, while its eligibility letter shows the CIN. The claim form asks for the number the payer assigned.
- What happens when the ID is wrong?
- The payer rejects or denies the claim. The usual X12 codes are CARC 31, "Patient cannot be identified as our insured," CARC 140, "Patient/Insured health identification number and name do not match," and remark code N382, "Missing/incomplete/invalid patient identifier." The fix is to correct the ID or the name and resubmit before the filing limit runs out.
- Is the member ID the same as my Medicaid provider number?
- No. The member ID identifies the rider and goes in item 1a of the CMS-1500, or the subscriber loop of an electronic claim. Your NPI and Medicaid provider number identify you and go in the billing provider fields. Ohio's wheelchair van form shows both, a 12-digit billing number for the rider and a 7-digit provider number for the company.
- Does Texas accept 999999999 as an ID?
- Only in one case. Texas Medicaid says that when a client is not yet eligible, a provider files with 999999999 or 000000000 as the recipient ID, knowing TMHP will deny the claim, and keeps the denial as proof the claim was filed within 365 days. In any other claim a nine-digit number must be a real one, and valid numbers begin with 1 through 7.
